quorum

So the new ZL1 comes on 305 rears, whilst our 2011 GT500s come with 285s plus a reputation for not being able to hook up.

I've done some research over the net, and people have successfully installed 305s on 10" wide wheels (I have the SVT package). In fact many wheels recommend 9-10" for a 305.

The question now is: which is a good street tire that's 305/XR20 (whatever the X is supposed to be to be same diameter as the stock wheel)? And what does "X" equal?

Thanks!!

nmd55

the issue with 305s on the gt500 wheels has never been the wheel width. Its the offset. If your offset is not correct the wider tires will be pushed out more towards the outside fender and will rub.

quorum

Thanks for the reply. What you've stated may or may not be the problem, but what is the solution? What do I have to do to get 305s on the back? (by steps)..

For example:
1) buy XYZ brand 20" rim with XX offset (what is XX? some examples of XYZ?)
2) buy ABC brand 305/X R20 tires (what is X? some examples of ABC?)

ps. 305 is an inch wider than 285s. That's a difference of 12.5mm on either side of the tire - by my eye, that shouldn't rub against the well.

thanks.

nmd55

i spoke incorrectly. If you have the stock suspension you will be able to fit 305s on the stock 19s and have no problem with rubbing. If you decide to lower your car (change the springs) you will have rubbing issues with the 19s.

quorum

The stock rear SVT wheels are 20", not 19".

nmd55

on the SVT-PP they are 20" on the non-SVT-PP they are 19"

The SVT-PP rear rubber is supposed to be much better although its still only a 285.
I would give it a fair chance before replacing them. Because those tires are very pricey too.

quorum

Okay, so a 305 tire can fit the stock 10" SVT width wheel. Now the question is: what is the "X" in:

305/X R20 ?? What does "X" have to be so that the wheel is the same diameter as it is now? Currently the stock SVT wheel is 285/35R20.

Thanks!

Snakebite64

I do not think the extra 10 mm will help you that much. Maybe drag radials will do the trick lol

Kotobuki

A 305/30-20 would be about 3/4" shorter overall (about 3/8" shorter sidewall), compared to stock. A 305/35-20 would be about 1/2" taller overall (1/4" extra sidewall) compared to stock. I don't know what the front tires are like, so the 305/30 might be okay, so long as you don't end up smaller than the front. The 305/35 would probably be the better choice, especially if the 10" with the minimum size for a 305 section width.

Obviously, all these numbers are just rough averages, and will vary from manufacturer to manufacturer, but they'll be close.

2008vistablue

I bought some nittos 555r in 305.....not the best tire out there but the price was good and sticker than the goodyears!