My rear 19x9.5 has a 265/35/19, I want to try a set of MPSCs, and the closest rear tire size they have is a 265/30/19. What kind of difference in the size will I notice, if any at all.

Thanks

You are reducing you rear diameter by 1" exactly and your load rating by 198lbs.

This is the best guide yet I have found for determining tire sizes. I live by it.

It's very clever and accurate.

Put those sizes in and you'll know exactly the changes and their affects.


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

Thanks! That guide is great.

Ferrari's and Lambo's have electronic traction control systems.

Improper tire sizes can trigger false info to/from those systems that can have less than pleasant results.

Thus, proper tire sizing is essential. This table does it all, and it is invaluable.

Another important thing to consider is unsprung weight=tire and wheel weight.

So, when changing wheels and tires it's good to know how the projected wheel and tire weights compare to the OEM wheel and tire weights. You want to keep this total mass as low as possible.

I'd stay away from 20" wheels because they are fragile. I went from 18's to 19's on my 360. It has made a considerable handling difference, but the wheels are very susceptible to rim damage which I have experienced due to the poor roads here in Northern Calif.

So, now I am going to different 19" rims but to much larger width tires.

So, this tire calculator has given me the answers I need.

Michelin is introducing the Z06 tire they make for Goodyear in their Pilot Sport Cup series in a 325/30-19 size. You could look at this size as a possibility. You will probably have to go to spacers for the rears, but Champion makes very nice Porsche rims and they can probably give you the offset you'd need for the wider tires to fit properly w/o requiring spacers.