Tire Size Question - 986 Forum - The Community for Porsche Boxster & Cayman Owners

Jaxonalden · 11-13-2010, 06:32 PM

What is the size difference between a 265/35ZR18 and a 255/45ZR18?

Chuck W. · 11-13-2010, 06:55 PM

Try this;

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

tonycarreon · 11-13-2010, 06:59 PM

265mm wide x 35% of it's width tall
vs
255mm wide x 45% of it's width tall

OR

10.4330708661 inches wide x 3.6515748031 inches tall
vs
10.0393700787 inches wide x 4.5177165354 inches tall

SO 265/35 is going to be slightly wider and have a smaller height than 255/45

Jaxonalden · 11-13-2010, 07:17 PM

Thanks Tony. There's a guy selling a couple of new Michelin Pilot Sport tires that are 255/45/ZR18. He's asking $200 and I was wondering if they would fit.

Would you put them on your car if your OEM size is 265/35ZR18

Topless · 11-13-2010, 08:19 PM

Nope, too dang tall. They are 27" diameter and your stock size is 25". Your car would look like a tractor.

For a comparable tire to your pilot Sports give these a look. Lots of guys like em.
http://www.tirerack.com/tires/tires.jsp?tireMake=Hankook&tireModel=Ventus+V12+evo+K110

Jaxonalden · 11-13-2010, 08:44 PM

Thanks Topless, those Hankook's have some great reviews. Prices are much easier on the pocketbook, two for the price of one Michelin PS.

tuanle16 · 11-14-2010, 05:12 AM

i just replaced mine with the hankook v12. they are pretty good so far. only had about 500 miles on them. but satisfied so far.

stevedollar · 11-20-2010, 01:46 PM

Beware that if you mix tire sizes front and rear (so there is more than 1% or 2% variance front to rear) your ABS will not work properly and your brakes will feel like they are not fully operating. I bought some wheels that had newish tires mounted on them, but the rears were 4% taller than stock. That was enough of a difference to make it so that the brakes felt like they were pushing back and not being fully applied when I took a freeway exit. Around town it made no difference. The Porsche dealer suggested reinstalling the old wheels and tires before bringing the car in, and sure enough, everything was back to normal. I ended up going to the tire size calculator on Miata.net and getting OEM size tires for the different sized wheels I had bought and everything is fine now. Good luck. PS the Michelin Pilot Sports are great. :dance: