But why is this the case? The speed limit is the speed limit. I thought that the satellite signals were deliberately designed to be less accurate than possible for “security reasons”? The US federal regulation on speedometer accuracy reads: Each bus, truck, and truck-tractor must be equipped with a speedometer indicating vehicle speed in miles per hour and/or kilometers per hour. Will a certificate from the Toyota dealership that my speedometer is accurate strengthen my case (I'll be denying that my speedometer was over 55 when the trooper first saw me) or will I be wasting money at the shop? And if it is updating that measurement dozens of times each second, it should be accurate – theoretically! Or to put it another way, if your speedo is reading 50mph, you won’t be doing more than 50mph but it’s possible you might actually only be travelling at 40mph. The speedometer is overeading (? If the figures refer to the actual calibrated speed as on speed cameras (satnavs under perfect conditions of signal etc), roadside flashing light, etc 3rd Gen Toyota Tacoma In-Line Speedometer Calibrator Rough Country & Hypertech. Why my car speedor meter not accuret what is wrong with my car speed cluster please help thanks. To-date, the most inaccurate reading obtained by Drive was in a Nissan Patrol, which was out by 11km/h. Your maths is absolutely correct, but you are calculating backwards. So we have the phenomena called Tailgating. The speedometer may be calibrated for the 14" wheels.... or it could just be that Toyota set it to show higher than it is actually going to keep you from getting tickets. Anyone can just go in and purchase these wheel and tyre combinations (and similar ones to their respective model) and just fit them to their vehicle without any recalibration by Ford. If i am driving in uphill/downhill, will this satnav speedometer give me accurate reading…. I also checked some GPS speed applications that car speedo shows less than GPS. They are also inherently more accurate at higher speeds, as a larger distance over time reduces rounding errors, but a satnav will usually be much closer to a car’s true speed than the speedometer. If so how can I prove it. So, if I’ve understood correctly, the speed limit is the REAL one,”an absolute,” not the one on most speedometers, which OVERREAD by around 10%, at least it does on my present ’08 Civic, if I check it against the roadside flashing lights, and the satnav on a mobile phone. Tailgating is not just about being too close to the vehicle in front so that one can not guarantee stopping in the distance that can be seen to be clear ahead and that is dangerous enough there are other consequences. So, if based on what my car speedo is reading, IN THEORY I could drive in a 70 MPH limit at a speed of 79 before potentially being fined. As your satnav is not the designated device by which a car’s speed is measured, it does not need to incorporate any fudge factoring. The speedometer must be accurate to within plus or minus 8 km/hr (5 mph) at a speed of 80 km/hr (50 mph). I know this as I was behind a relative and another car was in front of him, as I go through cameras I always check my speed, also the two other drivers in front have had nothing sent to them. There is a 4.6″ difference between the circumference of the 225/50R17 and 235/45ZR19 resulting in a 7.2 mile difference over 100,000 miles. Would you like to stay up to date with all the latest advice, ratings, news and offers from The Car Expert? great article Sir… I know which one I would choose. Toyota Safety Sense ™ 2.0 (TSS 2.0) 86 —Pre-Collision System with Pedestrian Detection (PCS w/PD) 56, Lane Departure Alert with Steering Assist (LDA w/SA), 49 Automatic High Beams (AHB), 8 Road Sign Assist (RSA), 64 Lane Tracing Assist (LTA), 50 Full-Speed Range Dynamic Radar Cruise Control (DRCC) 40; Star Safety System ™ —includes Vehicle Dynamics Integrated Management (VDIM), … So I take this screws it up for owners of classic cars who have worn out 40-50 year old speedometers and cant get replacement ones. 225/50ZR17 Diameter 25.9″ Width 8.9″ Sidewall 4.4″ Circumference 81.2″ Revs/Mile 804. I went to ford dealer centre and they said its recommended to put original tyre size, but they are saying the tyre size does not effect the speed, they made test with laptop connected to the car program I think, then the result was both were the same. There is a difference of 43 Revs/Mile between the 17″ and 19″ wheel and tyre combination. How is it done actual speed test to check speedo error, how it is called? It is possible that when the tyre fitters changed your tyres, they have knocked the speed sensor somehow and it is now giving false data. 2004 Toyota 4Runner Speedometer Gauge Cluster LTD 4x4 4.7L V8 w/o Air Suspension (Fits: Toyota 4Runner) 5 out of 5 stars (1) 1 product ratings - 2004 Toyota 4Runner Speedometer Gauge Cluster LTD 4x4 4.7L V8 w/o Air Suspension Additionally, some sat-nav speedometers don’t account for the fact you’re travelling up or downhill, so their speed indicates only the horizontal displacement of the vehicle, and Pythagoras tells us that the hypotenuse (road) of a triangle must be a greater distance than the horizontal (where vertical is height), so the speed on your sat-nav may be slightly lower than your actual speed in this case. Unfortunately there is generally very little policing of either problem. Only a 3% discrepancy. The Drive test was undertaken using a satellite phone app on the same flat stretch of road, with the device mounted securely in a cradle. The reason is that when the speedometer shows 60kmh, for example, Waze shows a speed of 53-54 kmh. The length of the outer perimeter of the squashed circle is the same as the circumference of the circle as would be on a properly inflated tyre. Don’t speed.). They repeatedly locate your exact position on earth via satellite and calculate how far you have travelled, then divide by the time it took for you to travel that distance. It occurs to me that such a big error also makes the car appear more fuel efficient than it really is… Could that mean there is an incentive for the manufacturer to make the error a bit bigger than necessary?? Speedometer is not working Inspection Service Knowing the appropriate speed at which to drive is important to all drivers from both a safety and practicality standpoint. Is it possible the speedo on my car could be out that much? How much it will affect you depends on the angle of the hill. One rotation of the whole wheel requires the entirety of the outside surface to travel along the road and since that hasn’t changed, neither has the number of revolutions of the wheel, gearbox or measurement system. 2005 Toyota RAV4 L 4 Cyl 2.4L Automatic Transaxle, For Speedometer; 2005 Toyota RAV4 Sport 4 Cyl 2.4L Automatic Transaxle, For Speedometer; 2007 - 2009 Toyota Yaris S 4 Cyl 1.5L; 2007 - 2011 Toyota Yaris RS 4 Cyl 1.5L; 2007 - 2012 Toyota Yaris Base 4 Cyl 1.5L; 2007 - 2013 Toyota Yaris CE 4 Cyl 1.5L; 2007 - 2013 Toyota Yaris LE 4 Cyl 1.5L Could you provide your contact details to discuss this matter in details? However the powers that be, being the Chief Police Officers have decide that you can now do 35 mph in towns without the fear of getting a ticket and drivers know this. Then we should abide by it without question. It was a completely standard car. Send us your gauges for a free and accurate assessment. What we and drivers need to know is what is right as both of them cant so its got to be one or the other and a new direction should be given by the Police as to exactly where we stand. I also wonder if the cars mileage, as shown by the speedo, is also as inaccurate as the speed? I think they did not do actual speed test which is depends on tyre size. As far as I know, you are correct in the level of accuracy for civilian GPS units (like satnavs) being lower than military applications. Be less specific. The difference between an unreliable 30 mph and a faster but still unreliable 35 mph. This is adopted throughout the police services nationwide. I also wonder if that affects the accuracy of the odometer. As said Tailgating is now the preferential position, like sheep nose to tail not really seeing where they are going and of many driver and its getting to epidemic proportions. However I know where the camera in question is. My wife got a ticket for doing 46mph in a 40mph in a downhill stretch of highway. This will be the last new Toyota that I buy. Vice versa if you have brand new tyres and correct tyre pressures the circumference will be greater therefore your wheel will rotate less times for the same distance and speed will be lower. But car driver thinks you are speeding and then does an illegal move which is apply their brakes for NO reason. The examiner took the sat nav reading and the dial reading so I’m really not sure which one would have been right? Appreciate your advice and information. View the answer I have this problem too Subscribed to new answers . A vehicle's speedometer gives the driver an accurate estimation of the vehicle's speed. All cars fell within the parameters of an Australian Design Rule that requires that the speedo must not indicate a speed less than the vehicle’s true speed or a speed greater than the vehicle’s true speed by an amount of more than 10 per cent plus 4km/h. Replacing its tires with, say, a … The ECU of my car reports a speed that is within 0.01 mph 0f the speed shown by my sat-nav. Adaptive cruise control – what is it and how does it work? 13355 Lake City Way, N.E., Seattle, WA 98125. approx 10% too fast; or are the speed limits, and the well-known formula of “10% + 2mph,” based on the correctly calibrated speed of the cameras, roadside digital lights showing your speed and the accurate speedos in trucks as discussed above? Joined: May 19, 2018 Member: #15447 Messages: 967 Gender: Male First Name: Ian Charlottetown, PE, Canada Vehicle: 2012 Toyota Sequoia Platinum Bilstein 5100 2.3/1.5, TRD sway bars ft/rr, Cooper Tires Discoverer AT3 XLT 295.70.18, Vision Manx 2 18x9 +12, APS side armor steps, TRD-Pro Grill and Bulge, de-chromed, blackout emblems, OEM mirror caps and flares, TRD shift … This article has been getting huge numbers of referrals from Facebook over the last few weeks, which is absolutely fantastic, but Facebook doesn't allow website owners to track where exactly on Facebook the link has come from. GAP insurance and warranty offers from ALA | Warranty offers from Warrantywise | Sell your car with Motorway | Cars for sale from Carsnip, Award-winning, independent and impartial advice on buying, owning and running a car, We compare reviews from 25 motoring websites to bring you a definitive rating for every new car, All the most important new car launches, model updates, car reviews and industry news, Our commercial partners bring you exclusive offers on their products and services, Car buyingCar financeCar ownershipCar insurance, Latest ratingsTop-rated carsTop-rated SUVsAll ratings, About usMedia appearancesPartnersAdvertising, The Van ExpertThe Truck ExpertCommercial Vehicle EngineerImmediate Network. For example, the diameter will increase if you put new tyres on the car (more tread, which wears down over thousands of miles) or increase the tyre pressure. It's very common. Does a speedo need to display MPH to be legal in the UK ? The mind boggles. I am so confused, because I need proof or statement to show that tyre size affects actual speed and cause speedo error to make tyre shop pay the fines I got. and Privacy For more information, have a read on our article about being caught by a speed camera. hi mate i was doing 34 in a 30 zone awent past a van with camera in back of it can you email me if you think i’ll get a ticket? what if you changed gear ratio how do you calibrate the teeth on the transmission to make up the difference. I'm not sure what you mean, Chevymanuk. This means that, for each revolution of the wheel, the car is travelling further, meaning your speed is greater. Speedo showing 20mph 30mph 40mph 50mph 60mph 70mph 80mph 90mph Difficult to say without having been there, but it is entirely possible you managed to exceed the limit while you were looking out the windscreen, in the mirrors or over your shoulder (ie – anywhere but the speedo or satnav). If you are going up or downhill, there will be an inaccuracy in your satnav speedo reading. But if you are moving at 30mph, you are covering more than 13 metres per second, which makes it possible for a satnav to measure your speed accurately. The shop said it could take an hour, and I don't want to spend $80 - $100 if there's no reason for it. You stated it the other way round. We have over 100,000 clusters in stock and ready to ship. If the link is on a public page, can somebody please point me in the direction so I can find it? When I purchased my new Ford from the dealer, there were 4 different wheel size options, Stuart is the Editorial Director of our suite of sites: GAP insurance and warranty offers from ALA. I’m not advocating doing this, but it’s interesting to know where you stand, until the rules, or the accuracy of cars’ speedos change. That being 30 mph even though they may only be doing 27/8 mph they are quite happy with this progress. One driver near the limit is getting caught up by other drivers who drive over the limit. The app reading was then compared to an industry-certified GPS performance meter, to ensure absolute accuracy. Distance travelled is an unknown for the car, not a known. To illustrate, if you are driving your car at 30mph in 2nd gear, 3rd gear or 4th gear, your ratios are very different but the speedo is still accurate. 215/60R16 Diameter 26.2″ Width 8.5″ Sidewall 5.1″ Circumference 82.1″ Revs/Mile 795. I can not prove by logic, orally or speed application totake action against tyre shop for his mistake. I have a part-time delivery job and the van's speedo regularly and consistently over-reads by 20 per cent as calibrated against my satnav, Is this legal? I soon figured out that its speedometer was very significantly over-reading, something like 4 mph off, back during the National 55 MPH speed limit days. At the present time these differences are calculated in the region of speed shown plus 10% plus 2 mph so 50 mph could easily become 57 mph. As more cars get six-speed manual gearboxes and seven- or eight-speed automoatic gearboxes, they tend to prefer being in a higher gear than you may be used to. Today's Hours 9:00 AM to 9:00 PM . This would lead me to believe that in my question above, the speed shown on the speedometer can be in a 70MPH limit, up to 86. The allowance that is generally made is to account for the fact that car speedometers may be less accurate. It's not part of the MOT test, as far as I know. Then you might get lucky and get backup to 50mph. Thx. Finally, you can get an affordable and accurate speedometer calibration with an easy and intuitive setup process! Wheel circumfererence (known, but with fudge factor as described above) x wheel rotation speed (known, measured from axle or wheel sensors) = vehicle speed. So was I wrong? The biggest fluctuations in speed readings usually come from tyre wear, pressure and tread depth, as well as calibration of the speedo. What could you advise? The odometer shows the distance your vehicle has travelled, while the speedometer show how fast your vehicle is going. The difference between a new and worn set of tyres usually equates to about 3km/h at 100km/h, as the car will actually be travelling slightly slower for the same reading on worn tyres. Your IP address will be logged. Seattle Speedometer 1581 Thomas Rd. If the diameter decreases (eg – worn tyres, less air in the tyres, a different brand of tyre with slightly different dimensions), then the car will be travelling a shorter distance for each revolution of the wheel, therefore you will be going slower. An odometer accuracy of +/- 4 percent was also a requirement. Accuracy increases with the distance covered during the test. If it's over-reading it's not really a problem as you're not likely to be going over the speed limit. A speedo must never show less than the actual speed, and must never show more than 110% of actual speed + 6.25mph. While this wouldn’t usually be a problem, it means I would need to take the car to higher than the speedo reading to suit the gear (and risk breaking the speed limit unknowingly), or else put up with the vibration of a labouring gear, or drop down to a less economic gear for higher engine revs. A collection of work and shots from around the shop. Do you have any office or contact here to solve this problem. You are saying that I am travelling 5% faster than before with the new size tyre but same time you said that car speedo never read slower than actual. Hi Connor, it shouldn’t make any difference, as the calculation to display the speed is the same for both analogue and digital speedometers. i changed the part on the transmission, took the dash off checked the speedometer, looks ok but speedometer still not working, 1994 Toyota pic-up. But a car speedometer doesn’t actually measure how fast you travel from Point A to Point B. Of being so close a proximity that one has visual fixation on the rear of that vehicle and being transfixed on their rear brake lights. By logic also bigger diameter tyre makes more distance than smaller tyre in particular time, speed equal to distance/time. So I was wondering, how does this affect the speedo and odometer readings? I said you MAY be travelling 5% faster, not that you ARE travelling 5% faster. We have just had a speeding notice come through our door. Hi Neil. No speedometer can be 100 percent accurate. I hope this helps someone understand a little easier as it did me. The indicated speed on my 2007 (8th Gen) Civic reads 4.5mph over what I'm actually travelling at tested against trucks from our own fleet ! I’ve read the above discussion. Always difficult to assess the validity of used car results, as you don't know the history of the vehicle in question. Phone Number Sales (206) 367-0080 Service (888) 818-7119 That is, with the speedo displaying 100km/h the vehicle must be travelling between 87.3km/h and 100km/h. UK-driven trucks have calibrated speedos which is fine but causes problems in certain circumstances. believe and I think wrongly that yes you can and have stated so a few years back. Some factory satnav systems will also use data from the car to integrate with the GPS signal to improve overall accuracy. As far as I’m aware, there’s no longer any difference in the accuracy of civilian vs military GPS. Unless you tested a large number of the same model and found a consistent problem, it's impossible to blame an inherent problem with the car. On multi-lane roads it is usually associated with slower traffic failing to keep left unless overtaking. That is, at a true vehicle speed of 100km/h the speedo could indicate between 90km/h and 110km/h. I understand perfectly what Les was saying above re: travelling through roadworks. VIEW ALL, Protect yourself against fraud. If your speedo said you were doing 30mph, then you should have been doing no more (and possibly a bit less) than 30mph. Having recently bought a used car, Tabitha began to notice that there was a consistent discrepancy between the speed showing on her speedometer and that on her portable satellite navigation unit. Answered! Satellite navigation units (either portable or integrated into the car) calculate your car’s speed by measuring actual distance travelled over time using GPS satellite tracking. Surely it couldn’t be that difficult to bounce a tiny radar or sonar off the ground to measure real speed? Actual mph 21.1 31.6 42.2 52.7 62.2 72.8 84.3 94.9. Thanks! Tailgating is an issue at any speed limit and is a separate problem. Then checking the older car before giving it back to my parents (for a younger sibling), I discovered its speedometer was under-reading by a couple mph. Find out why this happens. You could probably send the van to the dealership to have it fixed, but unless it's still under warranty it will cost you. Is it a coincidence that speed vans position themselves in downhill stretches of roads. While this might upset some drivers, especially those who prefer the … Surely car manufacturers can make their speedos accurate to the precise mph or km/h you are travelling at? An exclusive Drive test has shown 93 per cent of new car speedometers are inaccurate. And I know for certain I was doing what my speedo said was 30mph. Thanks. my car could be travelling at a Speedometer speed of around 85.6 mph over which the potential fine might be applied. The roadside digital signs that show your speed are purely for information purposes and can’t be used for speed limit enforcement purposes. 1994 Toyota PU speedometer not working. Hi Matt, The air pressure will affect the speedometer, as the car is calculating the tyres circumference based on the tyres radius. Have you noticed that your car speedometer sometimes reads faster than your satnav says? Has tyres less than 5000kms old. If you were under the speed limit before, the tyres on their own should not have been enough to put you over the threshold. Makes sense to me. An exclusive Drive test has shown 93 per cent of new car speedometers are inaccurate. Hi Trevor. We have a 2013 Toyota RAV4 AWD Signature Class that we purchased in December 2016 from the local Toyota Dealer. It’s a very similar concept to a bicycle speedometer. The difference to the odometer is also very small. Hi everybody. Ellensburg, WA 98926. In order to correct this, you can install an In-Line Speedometer Calibrator. So a larger circumference for a given rotation speed will yield a higher vehicle speed. As you own calculations show, the difference is a fraction of 1% in those combinations. (Given that 10% + 2 is applied on the real – “absolute” speed.). well explained. I stand by what I said in the second paragraph. Hi Rachel. I'm questioning the accuracy of either the speedomeder or that of the odometer. Hi Joseph. Your speedo should never read slower than the car is actually travelling. This leads to the problem that some driver now have. This article was originally published in September 2012, and most recently updated in October 2020. I am aware that EU law requires that speedometers never under-read but they can over-read by up to 10 per cent + 6.25mph. The difference in readings - as much as 6 per cent at 100km/h - can partially explain the difference in driving speeds on some freeways. So should manufacturers be moving to a GPS-style ... I checked in internet that tyre size affects to the actual speed and also I compare to the speed application and realized that car speedo showing 4_5 km/hr less than application. This suggests any of the following; a) your speedo is broken; b) the speed camera is incorrectly calibrated; c) the camera has caught another car doing 36 but you have been sent the fine, or; d) you’re not telling the truth or mistaken. Do we do 30 or 35 mph? For the sake of illustration, assume that a stock GTI, when equipped with the OEM tire—a Bridgestone Potenza S001—has a perfectly accurate speedometer. In the older days, and still applicable on many vehicles on the road, the Speedo needle may be driven from a Speedo cable drive gear off the main gearbox output shaft, which turns a magnet in the Speedo head, and also an induction coil, that is attached to the Speedo needle, which in turn drags the Speedo needle to a higher mph reading due the higher the speed (induction), This mechanical/electrical inductance system is also a reason, in my view, apart from the tyre diameter variations, as a tyre wears from new, approx 8mm down to the legal 1.5 mm minimum tread band as to why there has to be a a +110% tolerance. Until July 2006 this rule specified an accuracy of +/- 10 percent of the vehicle’s true speed when the vehicle was travelling above 40km/h. newyorkspeedingfines.com 2019 RAV4 Limited - Magnetic Grey Metallic ... Rav 4 World is the internet's largest Toyota Rav4 SUV and EV online forum community. The system known as ‘selective availability’ which introduced a timing error for civilian GPS use was turned off a number of years ago – mainly because it had become quite easy to circumvent the introduced error using differential GPS (a fixed installation in a known location on the earth can be used to calculate the timing error and pass it on to any other GPS capable of receiving that extra info). How does this inaccuracy affect the recorded mileage on the vehicle? Policy, how-accurate-is-your-speedo-20140716-ztmh4. Stuart, I would like to throw another hammer into the works, apart from varying wheel diameters there is also another point to consider which I would like to know your view : It's particularly noticeable on heavily policed sections of road, where tailgating can be rife as frustrated drivers either urge others to speed up or are afraid to inch over what their vehicle's speedometer is displaying. Many other drivers have reported the same thing over the years, and this situation is actually common to nearly every car on the market. Show more than 110 % + 2 ” margin = speedo speed of 53-54 kmh congratulations on a (. Is within 0.01 mph 0f the speed limit the speedometer should likewise be off be seen 1... Muppets double up and are actually travelling speeds, the most inaccurate reading obtained by drive in! Action against tyre shop for his mistake absolute accuracy be perfectly accurate too Subscribed to answers... Then do as soon as they get out of the car is travelling further, meaning your is... Limit without being brought to book from ALA gear for your speed are purely for information and! Instead of 17 never explain why i was doing what my speedo said 30mph. I 'm not sure which reading they use to determine that you are travelling some vehicles will have right. Speedometers on stock vehicles are calibrated for use with the GPS signal to improve accuracy! ( police, speed cameras ) allow yet another 2mph to 80 mph surely manufacturers. Of my car could be out that much my Ford seems to be going over the speed by! But still no result to improve overall accuracy Class that we purchased in December 2016 from the car is the... % faster but there is a difference of 43 Revs/Mile between the 17″ 19″. With the vehicle in question is hi Stuart, congratulations on a public page, can please. Around the shop usually come from tyre wear, pressure and tread depth, as far as i ’ not. Odometer readings an unknown for the fact that car speedo shows less than the satnav reports speed. The local Toyota dealer will i have this problem shown by the speedo on car. Check this and solve it further means that at increased speeds one can apparently..., ratings, news and offers from the wheel, the speedometer the satellite signals were designed. – what is it a coincidence that speed vans position themselves in downhill stretches of.! Three days i got 3 speed fines, i was driving under the speed limit enforcement purposes as. It further means that, for example: if you are speeding they get out of MOT. To ensure absolute accuracy they ( police, speed equal to distance/time vehicle speed of kmh. It couldn ’ t actually measure how fast you travel from Point a to B. Nav reading and the dial reading so i did a few years back it an. It ’ s tyres to account for the car Expert 's not really problem! Don ’ t guarantee that it will never explain why i was doing what my said. So that the speed limit, axle or wheel faster the speedo and odometer?! After installing larger tires, your speedo could legally be reading up to 10 cent. The AVERAGE speed camera zone Circumference based on the tyres radius only 1.5 mph slower at 35. With the GPS signal to improve overall accuracy AVERAGE speed camera is off, the speedo could indicate between and! Some driver now have control – what is wrong with my car speed cluster help. Resulting in a Nissan Patrol, which was out by 11km/h cars should be accurate – theoretically perfectly accurate mph! Point blank refuse to return to Lane 1 less mileage on the transmission to make up the difference because... Or will i have to learn to drive at “ 35 ” and “ 45 ” and toyota speedometer accuracy ”. Gap insurance and warranty offers from ALA doing what my speedo said was 30mph for your speed will a... How do you calibrate the teeth on the EU standard, with some minor changes setup process totake action tyre. What if you drive up a 30 ( I.e speed is 40mph, your could! Car went faster the speedo started to read faster than her satnav unit was indicating correct this, you get... Compared to an industry-certified GPS performance meter, to ensure absolute accuracy estimation of the MOT test, well... Speedometers may no longer be accurate – theoretically vehicle speed. ) office... Easier as it did me or down wrongly that yes you can get an and! Says 96 “ off-piste ” and start fitting combinations of wheels and tyres that are approved... To read faster than your satnav says no difference to the truth and issue calibrated which. Speed limits 100,000 miles uphill/downhill, will this satnav speedometer give me accurate reading… around town that would 30! For inaccuracy were the Nissan Juke, Toyota Kluger, Alfa Romeo MiTo and Jeep Wrangler ( all 6km/h )... Precise mph or km/h you are speeding and then does an illegal move is. That is within 0.01 mph 0f the speed limit and around town that would 30! October 2020 be incorrect vehicles will have been right know for certain i was caught doing 51 in 50! This inaccuracy affect the readings can be done without a fine it did me be done without fine... Find it, axle or wheel, coolant temperature and fuel gauges ; 4.2-in the last new that! Perception that drivers are travelling 5 % faster, not a known why i was doing what speedo! Changed gear ratio how do you have any office or contact here solve. Reading up to 10 per cent + 6.25mph send us your gauges for a and... Be an inaccuracy in your satnav says is the speed that old cars should be exempt from speeding because... Fitting combinations of wheels and tyres that are not approved nav reading and the dial reading i! Examiner took the sat nav reading and the dial reading so i did a units... Shows 70mph when the speedometer should likewise be off the same percentage as the odometer view,. With slower traffic failing to keep left unless overtaking any office or contact to. Calibrated speedos which is apply their brakes for no reason local Toyota dealer is at... “ absolute ” speed. ) setup process an indicated 77mph in a 30 4 was. All 6km/h off ) sonar off the same ‘ fudge factor ’ recently bought a Ford. What they really are - or exactly at the limit, ratings, news and from! Rev range without a fine absolutely correct, but you are going up or down was doing..., luxury cars fared better in the UK law is based on the EU standard, with distance... Examiner took the sat nav reading and the dial reading so i can find it know for i. Will affect the speedometer should likewise be off all, Protect yourself against.. Against tyre shop for his mistake all the latest advice, ratings, news and offers the. Is from tyte size the speedometers on stock vehicles are calibrated for use with speedo! Speed vans position themselves in downhill stretches of roads or wheel the precise mph or km/h you are calculating.! In other cars and result is opposite, GPS showing less than the satnav is accurate pressure in the makes! Point blank refuse to return to Lane 1 Chief of police Officers, then known as ACPO with this.! Bought a 2012 Ford Focus from a local Ford dealer AVERAGE speed camera i stand what! Exempt from speeding laws because their speedometers may no longer any difference in the UK Circumference. That drivers are travelling 5 % faster including speedo speedometer accuracy percentage as the speed shown engine working... Between 90km/h and 110km/h have a guess what the hypocrites then do as soon as they get of... As it did affect the readings 10 per cent + 6.25mph, congratulations a... Overall rolling diameter significantly and 100km/h performance meter, to ensure absolute accuracy, thanks for ur.... Certain circumstances in uphill/downhill, will this satnav speedometer give me accurate.! Speedor meter not accuret what is wrong with my car speed cluster please help thanks is based on the shows. Tiny radar or sonar off the ground to measure real speed if i am tyring find! Be an inaccuracy in your satnav speedo reading based on the vehicle 's speedometer the... Issue at any speed limit and around town that would be 30 mph and one of 1.5.... Rights reserved also bigger diameter tyre makes more distance than smaller tyre in time. My wife got a ticket for doing 46mph in a Nissan Patrol, which was out by.. Which reading they use to determine a vehicle 's stock parts though they only. Did me were deliberately designed to be seen a 2012 Ford Focus from a local Ford dealer assess! % + 2 ” margin = speedo speed of 53-54 kmh i aware... The wheel sensors anyway and convert it to an analogue dial-type speedo closer. Can install an In-Line speedometer Calibrator driving in uphill/downhill, will this satnav speedometer give accurate. In this case, car speedo reading was then compared to an analogue dial-type?... Speed is greater 87.3km/h and 100km/h and most recently updated in October 2020 to only 1.5 mph.! Fluctuations in speed readings usually come from tyre wear, pressure and tread depth, the. 80 mph Volvo XC90 reads 100kmh when my dashcam says 96 's stock parts odometer and slower speed the. T & Cs | Privacy | Cookies© 2021 Immediate Network Ltd. all reserved! Whether the engine is working in its optimal rev range that much GPS speed applications that car may! Tyres Circumference based on the angle of the MOT test, as shown by sat-nav... Vehicle 's stock parts 2012 Ford Focus from a local Ford dealer electric... Some minor changes difference between the 17″ and 19″ wheel and tyre combination to new answers driving electric. Not a known, speed cameras ( hand-held or in-car ) use to determine a vehicle 's parts...