That what my speedometer seems to be off by....anyone else

At an even 3000 rpm's in 5th my Speed 'O shows 66-67 and the true speed is 63.

This assumes that the NC DMV's Roadside Unit is working correctly.

 

My speedo is optomistic as well by about 1%. At least according to my handheld GPS.

That's with the 16" wheels and run-flats. Haven't tried the GPS with the 15" holey's.

 

I guess I should have stated:

15" Seven Holers

Cooper - No'S'

 

Due to European law that makes it illegal for a speedometer to read under the current speed, most European cars have their speedometers intentionally adjusted over. However this does not apply to trip computers / GPS. Here is a thread on this issue.

https://www.northamericanmotoring.co...amp;topic=5177

 

i was told putting 215/45/17s allows the best of speed readings to be accurate

 

Thanks, mikemsd...

I did try to do a search on this topic before I posted - but I guess I didn't look deeply enough!

 

My 205/45/17's give me 71mph at an indicated 74.

 

The local police had one of those radar things to show you how fast you are going near my house for a couple days, my car is about 5-6 miles off. I was going 45mph, but my car said 50mph. (sometimes 51mph) My tires are the 16" performance run flats.

 

My 2000 Accord was almost 10% off - both by the portable radar signs and time vs distance. The MCS w/17" all seasons seems much closer, about 2mph at 50 - 60 according the the portable radar. I've noticed that I'm running a slower indicated speed in the same traffic conditions w/the MINI.

 

after i put my 215/45 on later this week, i will report back to camp

 

i got the same deal going on over here in hawaii. my MC CVT with 16" performance run flats reads 55 mph, but the roadside speed reader says 50 mph.