I have a 92 prelude which is stock height. I am gonna add 18s soon and was wondering how much i will have to lower to car to get it at stock height. I was thinking...
15" has a radius of 7.5 and 18 has a radius of 9; thus that car would be raised 1.5" by 18s... is this correct or do the tires play a factor or anything like that.

Thanks, jordan

 

Tires get thinner sidewalls as the rims get larger.
This is to maintain the stock wheel circumference so that your speedometer works, and the gears are correctly in their power range.

Here's how tire sizes work:

EXAMPLE: 205/40/17

205 is the width of the tire in millimeters
40 determines the sidewall height. in this case it is 40% of 205mm
17 is the rim size that the tire is for in Inches

There will be some letters in there to tell you the speed and treadwear ratings of teh tire.

*NOTE* while tire size changes when the rims get larger or smaller to maintain the wheel's circumference, the resulting circumference will vary slightly fom stock. Usually only enough to change the speedo by about 0.2mph @ 60mph.

wotteg

 

The term is called “plus sizing”. There are some good tutorials on tirerack and discount tire directs websites.

I suggest doing some research before throwing down all that cash. Find out about wheel offsets and wheel weight.

I recommend 17’s on your prelude because the ride won’t be as harsh, the tires are cheaper than 18’s and with 18’s, the sidewall is going to be so short you can ruin your rims if you hit a big pothole.

But that’s my $.02