[RedHardSupra]

You're probably not going to like this one, but another VERY good choice for your 17x11 rims and intended use would be the Kumho Ecsta MX in 285/40-17. It's going to look more like a Formula One or GT race tire instead of a fat drag tire, but it's still a lot of rubber. It will probably handle better than the 315 Sumitomo and outperform it in the rain too. It certainly won't tramline as bad as the 315s. AND, it's cheap!

I saw this post in another thread, and it got me thinking: would 285/40-17 Kumho MX be a good choice for 17x9.5/17x11 afs zr1 combo? I like 315s on the back, but the tire selection sucks (especially considering the price). So would it be possible to put the 285/40/17s on both the front 9.5s and rear 11s (pics anyone?) and actually keep it balanced and safe to use in track situations? what's the point of the wider wheel then?

It's a strange, un-happy middle for me, as I would have the weight of the big wheel, but the grip of the smaller wheel. So I either go to 17x9.5s everywhere, or bite the bullet and pay a grand for a set of KD's and be done?

Please enlight me.
Dazed and Confused,
Marcin

[sgarnett]

Yes, a properly set up, neutral car can exhibit both severe understeer and severe oversteer depending on driver input, though a smooth driver won't get too far from neutral (some manipulation of the balnce is desireable, as in trail braking).

One rule of thumb - the rim width should ideally be no less than about 90% of the section width.

Another rule of thumb - the ideal rim size for a given tire is usually somewhere between the middle and top of it's rated rim size range.

For example, a 275/40-17 is rated for a 9-11 rim. A 10" rim is probably about right, but they aren't very common in our bolt pattern.

The 315 is a decent match to the 11" rim, but 315 isn't a great size for street driving (neither is 275, really).

FWIW, even with stiff race tires, a 265/45-16 on a 16x8 rim doesn't really provide any more grip than a 245/45 tire on the same rim. The main difference is that the 265 will be a little softer, so it may work better at the rear for putting power down in a straight line, while the crisper 245 at the front will probably turn in a little better.

In general, wider tires at the rear will cause understeer. However, as tires wear and harden they lose grip. When you can't rotate the tires you can't keep the aging balanced either, so the handling balance will tend to shift over time.

Choosing tires is not an exact science (IMG:http://www.frrax.com/rrforum/style_emoticons/default/smile.gif)