I'm Thinkin Of Getting 20" Vossen CV3 Rims.

I Think I Have The 17 Inch Stockies And I Am Wondering If I put 20 Inch Rims On Mt IS250 AWD, Will There Be Any Speedometer Error?

 

It will be off by a few mph, so it will read 60mph but your going 56

 

At the end it depends on the size of the tires you go with but it will probably be off by a few MPH.

 

Won't make a big enough difference.

 

You could use tire calculation to see how different with new wheel

 

How about 19"? Same difference?

 

How "off" it is depends not on the wheel diameter but the total diameter of the wheel and tire.

Nobody can give you a real answer without both.

You can compare sizes yourself using a calculator like this one:

http://www.miata.net/garage/tirecalc.html

 

Once you go with the recommended tire size that keeps the overall diameter around the same as OEM you will be fine.

Thanks for the link Kurtz!

We recommend
245/30/20 and 285/25/20

 

Like Kurtz said, wheel size doesn't matter. Tire diameter does.

 

^
I think you mean to say both because it's the overal diameter of wheel + tire which will determine it.

 

not really, as you can have multiple tires with the same diameter for multiple wheel sizes. so it is only dependent on the tire

 

Yes, this is true in some aspects. As for my explanation, I am assuming OEM stock applicable sizes to retain the speedometer.

 

Hm, so after years and years of driving, your ODO will show a lot more miles than actually traveled.

 

I would Prolly Go Low Profile.
I Guess I'll Have To Set That When I Get Them....

Thnx Guys..

 

just get the wheels you want.. drive past one of the radars they lay out on the streets that show your speed and fig the difference. and you should be going slower then your car says. so you have a little cushion for speeding