Confused on tire/wheel sizing

John_H · 06-09-2009, 09:52 PM

I'm totally confused on how tires and wheels are sized.

Okay, the SS has 245/45ZR-20 on front and 275/40ZR-20 on the rear and the wheels are 20" X 8" on the front and 20" x 9" on the rear.

So, I don't know how you would size the tire with the wheel. I understand the diameter, but the width difference in the wheel and tire throws me off. How do you properly size the tire and wheel?

The reason I bring this up is because in the interview with Pete from Peddlers, he said we can have a 10" front tire and a 12" rear tire. I'm assuming he meant the the tire width, but what width should the wheel be? Also, does anyone know how sidewall height affects handling. I know the larger the sidewall, the better the ride is, but what is the optimum side wall height for handling?

Thanks

MetalDragon · 06-10-2009, 03:24 AM

I believe he was referring to wheel width. As far as tire to wheel...I've been told that a good rule of thumb is to keep your tire width within plus or minus half an inch of your wheel width, but 275mm is about 10.8 inches on a 9 inch wheel, so who knows. If you follow this pattern...and you put a 12 inch wheel on, it would seem you could possibly put up to a 355/30/20 and have nearly identical diameter to stock. Too much or too little and the tire won't seat on the wheel properly, though and a 305/35/20 is almost exactly 12 inches wide with virtually the same diameter. Seems like there's a good bit of room to play with.

As far as optimum height for handling...technically, a strip of solid rubber wrapped around the wheel. It depends on what you want to do with it and how much of a trade off between performance and comfort. Generally speaking, less sidewall equals less "float" but rougher ride.