I've gone by three different radar guns (the ones they put on the highway or in a residential area to show you your speed and they blink at you if you are over 60mph) and each time, my speedometer has read lower than my actual speed.

I was indicating 29mph, radar said 31

Indicating 61, radar said 66

indicating 58, radar said 63


I was driving behind my friend who was driving his dad's 1985 Mercedes AMG. the speedometer had just been recalibrated. I was keeping pace with him when he was doing 70, and my speedometer was at about 65.


Who can do this the best? Is there anyone other than a dealership who can do this? Also, what am I looking at for cost?

Thanks!

 

Do you have stock tire size?

Get used to it, nothings as dead on as we all would like.

 

same size as stock...not the stock tires. (NITTO NT450)

the speedometer went out of calibration when I had my new axle put on.

 

By default, our speedometers are good for at least +/- 2 mph, so you are outside the range by 3 mph worst case... IMO it may not be worth the trouble getting it calibrated...

 

even with my 18's and tires to match stock specs, my speedometer is right on the money. Stop by at the stealership and get a QUOTE then shop around with that price in mind

 

... What are you saying?


If your tires match stock specs ( read: total/overall outer diameter) it wouldnt matter what size of wheel/tires you had...

 

pop off clear gauge cover
turn needle slightly past the stopping point

 

yeah..but it's just a pain when you think you're driving 70mph in a 70 speed limit. You know there's a cop ahead of you clocking everyone as they pass. You're following 2 guys who you think are doing 70, because that's what you're indicating. And both of them are the ones getting pulled over because they were the two right in front of you getting clocked...that was when i started getting clues about this being inaccurate. It gets worse the higher you go. In Texas, they start pulling you over when you're 6mph over...but that almost never happens...except to busses and 18wheelers. They normally at least go to 8 or 10 on the major highways before the lights come on.

so my best guess is that when i thought I was doing 70...i was doing at least 77 or so...