Reply to "18"/19" Wheel and Tire Advice"

MotorCity72,

Is that you Walter?

On the second page of the thread listed below is a formula to determine tire width, sidewall height, and overall diameter. It will help you narrow down tire selection:

http://pantera.infopop.cc/eve/forums/a/tpc/f/6450045562/m/6490069782/p/1

I went with Kinesis K58's for the front, and K59's for the rear. This is their 5 star pattern wheel. They measure 18 x 11 and 19 x 13. The tires are Michelin Pilot Sports, 285/30/18 front, and 345/30/19 rear.

The formula shows the tires to be:
Front: 11.22" wide, 3.37" sidewall, 24.73" overall diameter.
Rear: 13.58" wide, 4.07" sidewall, 27.15" overall diameter.

The difference in sidewall height is .70" (almost 3/4") Look in the thread below at a profile picture of my Pantera to get an idea how the sidewalls relate to each other front to rear.

http://pantera.infopop.cc/eve/forums/a/tpc/f/765004...860058643#3860058643

When you decide how much of a difference in sidewall height you like, use the formula to narrow down which tire sizes will look best with each other (front and rear). I think a 9" rim in the front is about the max you can go on a stock bodied car. If anyone knows otherwise, please chime in. If you're going with a 19" rim on back, I believe that diameter will clear the upright/lower control arm nuts, so you can go 13" (or wider). The tire height may be an issue though, so measure very carefully.

If you want to know if a 20" tire will fit the rear, use the formula to determine overall diameter. For instance, a 345/25/20 is 26.9" tall with a 3.4" sidewall. A 335/30/20 is 27.91" tall with a 3.96" sidewall. Probably too tall. This tire wouldn't even have fit in my wheel opening. The front has it's own limitations. If you go too tall overall, the tire will hit the underneath of the fender when the suspension travels up high! You also have to worry about rubbing when turning, and the ride height being increased too greatly. Goran Malmberg feels the magic number for the overall diameter in the front is 24". He wrote a whole technical article about tire sizing which can be found here:

http://www.panteracars.com/Goranwheels1.pdf (Note it's a PDF file)

There was a balance that I was trying to strike in terms of sidewall height to rim diameter. I wanted to go as far as I could diameter-wise to accentuate the GT5-S flares, but I still wanted to retain sidewalls that looked in proportion (not like rubberbands), and gave me a livable cushion too! I feel I achieved my goal, but it took alot of formula use and measuring

Play around with the formula, and I bet you'll narrow down pretty quickly what will work for you.

Michael