Hey I just bought some 205/40/17 inch wheels/tires and I'm wondering what the difference will be in my speedo from a stock 1989 crx si? I know theirs a calculator somewhere online for this can anybody help me out I dont wanna end up with a ticket because of something dumb like this.

 

Why would you get a ticket?

 

I knew my speedo would be off and was thinkin that I might be going faster then my speedo reads but I just remembered it will only read slower with the wheels I got.

 

if it reads slower, than that means you would be speeding...

 

Yeh ok I think we can all see that I didnt sleep much last night hahaha ok well if anybody knows roughly what the speedo would be off by just let me know lol

 

The stock 185 60 14s will rotate 910 times per mile. The 205/40/17 will rotate 886 times per mile. So with the ratio of 886/910 at 60 miles an hour your speedo will read 58.4 MPH.


The formula is 886/910 = 0.9736

Multiply the indicated speed by 0.9736 or 60 MPH x 0.9736 = 58.4

BTW i got the revs per mile on the tire rack site. tirerack.com

 

I realize you aren't asking an opinion of your purchase, but I have to say something. 17's on an 89 CRX is WAY too big. The tiny brakes behind them will look gay. That, combined with with small size of the car, plus the speedo being thrown off, it's just not practical. It's going to look silly.

Unless of course it's lowered and has a big brake kit.