25/28. Believe it or not the speedometer reading 4 MPH higher than your actual speed is normal for this vehicle. Speedometer... BMW miles per hour versus actual MPH 7 mo ago. So if your true speed is 40mph, your speedo could legally be reading up to 50.25mph but never less than 40mph. And I'm usually bold enough to use the GPS speed to set my cruise rather than speedometer, without getting pulled over. Going from 275 R 50 -- 20s to 285s will give you about 1.8% in correction. Location. Let me explain. I believe the 195/60R15 (863rev/mile) tires turn more than 185/65R15 (855rev/mile) at the same speed, therefore the speedometer reading with 195/60R15 is higher than with 185/65R15. If the speedometer reading is lower than the actual speed, the speedometer is slow. If my speedometer says I'm going faster than I really am ... Best to develop a good sense of speed as a backup plan. If the problem is exponential (the gap between actual speed and displayed speed gets greater the faster you go) then the problem is the speedo gear in the trans. The speedometer of a car reveals information about the instantaneous speed of your car. It shows your speed at a particular instant in time. On the average, your car was moving with a speed of 25 miles per hour. My current car now is spot on with gps reading. Thus, with each revolution you are traveling further than before. The current UK law is based on the EU standard with some minor changes… A speedometer must never read less than the actual speed or show more than 110% of actual speed + 6.25mph. #1. That means if say your speedo is reading 65 and your GPS says 62, that also means when you've driven 65000 miles on your odo, you've really only traveled 62000 in real life (and in any other car). ), erratic speedometer sometimes registers higher or lower than actual speed, then returns to normal, then to faster or lower than normal, for 10 to 30 seconds, the cable ends look good, fit into the speedo head and transmission The actual speed seems to be consistently 3-4 mph faster than indicated on the cars speedo across the board. A driven gear with fewer teeth will speed up the speedometer reading; more teeth will slow down the reading. GPS, on the other hand, uses a purely mathematical technique to measure the speed of the vehicle and is therefore more accurate than a speedometer. Still missing the days with the Benz, it kept me busy. if you read the post correctly his wife was traveling 60 next to him and his speedometer was reading 71 while his c3 was traveling 60 also. Many jurisdictions place strict limits on speedometer accuracy - but the range is not symmetric typically the legal range for the speedometer display is 100-110% of actual speed. Speedometers are not allowed to read lower than the actual speed of the car, but they are permitted to indicate a value that is 10% higher than the actual speed, plus 4. Car speedometers will always be inaccurate, because your speedometer is measuring how fast your tire rotates. I just put new tires on (OEM 245 75R16) but there has been virtually no change. Over Reporting speedo (speedo 120kmh actual speed 115kmh) 2. The actual run out of the tire can be as much as 2 to 3 inches less than what the circumference of the tire measures. I am seeing an issue on my 2005 Freestyle AWD with the Speedometer Showing Faster Then Actual Speed by 5 MPH. To calculate the actual speed of your vehicle, you simply determine the ratio of the circumference (pi * diameter) of the … I am having an issue with my speedometer, it reads slower than my actual speed. Speedometer reporting faster than actual speed So over the weekend my wife, brother-in-law, and I were sitting around talking and all came to the same conclusion that our speedo's were off, saying we were going faster than we actually are. The tests were done with the stock 1.95" tires and the readings were taken using throttle only at full tilt. If the speedometer reading is higher than the actual speed, the speedometer is fast. Up-sizing, or installing a taller tire, will lead to a speedometer reading that is slower than your actual speed. BMW does not allow the dealer to "fix" it. I.E. Apr 27, 2013. I replaced the speed sensor located in the transfer case and still no luck. I proved this my comparing my Speedometer to the speed being displayed on my Garmin GPS. Image (Click to enlarge) SPONSORED LINKS. Bigger tires will cause your speedometer to register a speed that is slower than your actual speed. Brought car back to the dealer explaining the inaccuracy, was told verbally speedometers are gauges not meters and can only be designed to guess the actual speed, they cannot report actual speeds. Answer (1 of 5): No, that’s not particularly true. My 94 Fleetwood is the same as well. To put it another way, if the speedometer says you are doing 20 MPH, you're actually going 19 MPH. Up-sizing, or installing a taller tire, will lead to a speedometer reading that is slower than your actual speed. They send a signal to the ECM which then sends out another signal to the speedometer. Reaction score. My speedometer reads 3 miles an hour faster the my actual speed at any speed. This is why the speedometer on my '7 with 35s and 4.10s is correct with no speedo gear change. This can also affect your odometer and speedometer as larger tires will have a larger circumference, causing you to travel a little bit further per each complete tire rotation. In these transmissions, each tooth added or deleted changes your speedometer reading. The UK law is based on the EU standard, with some minor changes. I have a 1993 Cummins 4x4 with the 5 speed manual tranny. I have a 2004 2500HD pickup with diesel and 95,000 miles. Page 1 of 2 1 2 Next > Does the speedometer read 30mph when you are stopped? This speed signal is a big factor in the overall performance equation. Where I live, 75 won't get you a ticket, but 80 will. The causes of a bad speedometer will typically be found in these four things: A typical VSS. That means less teeth, not more. Speedometer shows 2 MPH faster than actual speed Discussion in ' Gen 3 Prius Technical Discussion ' started by windmilljumper , Sep 29, 2009 . Check out the diagrams (Below). #1. Apr 18, 2014. When the GPS reads 140 km/h, the speedo reads 145 km/h. 1 Answer. The … As long as a car is maintained at factory specs, its speedometer should continue to register vehicle speed within this range. My vehicle is a 2004 Jeep Grand Cherokee Limited, with the 4.7L, V8, SOHC, 16V engine, and has the "All-The-Time 4WD" transmission. Toyota's display of higher than actual is in line with the norm. Your speedometer is reading how many revolutions your tires are making not how fast they are spinning. If you want to know with GPS verified accuracy, grab a couple of zip ties, download a free speedometer app, zip tie your phone to your bars (so you can see the screen and the speedo at the same time), turn on the app (turn off the auto … So they set up the speedometer to never be low for any tire that will fit in the wheel-well. Currently I have no speedometer and despite the transmission shifting very well, it skips second gear consistently (no intermittent functioning). 2. It combines this data to send the speed reading to the instrument cluster. The speedometer is original but at some time or other the c4 transmission has been changed out. If it … There is apparently a law in Germany that the speedometer cannot read less than the actual. Dec 3, 2012. If you regear proportional to tire size increase, then the speedometer will remain correct. But that’s the key thing: your speedometer needs to be reading low. Tonight I was … read more Thus, with each revolution you are traveling further than before. Love my ride so far except. GM was sued, and lost, for certain models which displayed under actual speed. The law for car speedometers in the UK. So according to this you could be actually going faster than your speedometer is reading, and still be within federal regulations. The following numbers are indicated speed / GPS speed: 20/22. Below are some examples of what it's reading. Drove an 06 LTD FWD from July 08 to August 10, moved on to a 2011 Flex. Your odometer will read lower, too. The Turbo 350, Powerglide, and GM four-speeds have driven gears that have anywhere from 17 to 25 teeth. this would be correct with 355 gears installed inplace of 308 without changing the speedometer gear. The UK law is based on the EU standard, with some minor changes. 60/65. This is why the speedometer on my '7 with 35s and 4.10s is correct with no speedo gear change. I have a 2009 GMC Sierra SLT 1500 with an edge performance chip and 20" tires and my speedometer. ... At 50 I was about 1 mph faster than the speedo was reading. May 23, 2019. bobgto65 Post subject: Re: Speedometer reading high. On a previous vehicle my reading was about 2kph faster than actual which was close enough, I put on winter tires, same brand, same size. If you regear proportional to tire size increase, then the speedometer will remain correct. If my speedometer says I'm going faster than I really am does that mean my odometer is registering more miles than I'm really driving? Speedometer reading at least 10% faster than actual speed. It will affect the speedometer. When you go to bigger tires the circumference of the tires is larger, meaning the distance around the tire is longer. By Josh16. By the way tires are the original size as stated in the car manual. Howdy, Ever since I bought my truck the speedometer runs about 10 mph higher than the actual speed, with the speed difference growing the faster I go until it's about 15 mph off from the actual speed at 70 mph. I've repeated the tests using a dash cam with GPS speed so you can observe the actual speed and the actual speedometer reading and clearly see they are way way off. When you add larger tires to your Jeep, the speedometer is reading slower values on a LINEAR slope, it doesn't read "5-7mph off" all of the time, only at a certain speed. I sent the cluster off and had all of the motors repaired and calibrated with the correct tire size 265/70R17. For example, I'll set my speed to 75-76 GPS, where my speedo says 79-80. I recall reading an article on C&D, the test result of speedometer accuracy shows all cars read faster than their actual speed with Bimmer being the extreme, read almost 10% faster. Perhaps a half a percent due to worn tires before. Back to the basics, if your speedometer is indicating too slow for a given roadspeed then you have to turn it faster. The speedometer is slow and Honda also got sued for it, because your speedometer is with your bigger. Only at full tilt indicating vehicle speed rather than a mechanical cable for larger tires, i 'll set speed. 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