Open Road

I bought a set of Cup 2 wheels from Gary Knox some years back that included 911 Winter wheels, with correct offset but 8" wide, for the front.

At the time Gary recommended I get a 235/45-17 tire for the fronts, keeping the stock 255/40-17 at the rear.

My mechanic gave me a hard time about it, saying I shouldn't get a taller than stock tire at the front but I went ahead and purchased a set of Michelin Pilot Sport All Season - which he also gave me a hard time about because 'A sports car shouldn't have a tread pattern that ugly'.

Everything was fine for the 4 driving seasons they lasted - they wore out in the center on the rears after about 20k miles

When it came time to replace them I went with his recommendation of Bridgestone Pole Position S04 in the stock sizes. Honestly, it may have felt a bit 'lighter' in the front but the tread wear was horrible, needing replacements after 1 season and 5k miles, again with the center of the rears worn out, even with a lower tire pressure than the 44psi in the manual.

So what's the lists' opinion here? Go with the wider tire to take advantage of the 8" wheel? Stay with stock sizing?

Tire Rack does have Michelin Pilot Sport All Season in both sizes, along with PS2's in the smaller size.
For Bridgestone they have RE71's in both sizes but the wear rating is half of the Michelins so I'd be looking at another quick replacement.

Please humor my spring neurosis and let me know what you think...

-Tom
89 S4 Black/Linen 178k miles

Summary answers to your questions:

Start all pressures at 36 PSI and go from there.

235/45-17 is completely fine on the front with 8" wheels. The more front tire you can stick under a 928 the better it works.

Modern UHP all-seaons tires give up very little from Summer tires on the street.

tlebovic wrote: ↑Fri Feb 28, 2025 3:08 pm At the time Gary recommended I get a 235/45-17 tire for the fronts, keeping the stock 255/40-17 at the rear.

Right. Because Gary knows that more front tire (with appropriate wheel) on the front of a 928 is better.

tlebovic wrote: ↑Fri Feb 28, 2025 3:08 pm My mechanic gave me a hard time about it, saying I shouldn't get a taller than stock tire at the front

That is a recommendation without context. The primary factor in changing tire sizes on one end or the other is to keep the ratio of rolling diameter front-to-back within 5% of the stock front-to-back ratio. Why? ABS. 235/45-17 on the front is within this 5%.

On a 928 the wider the tire and/or the taller the tire on the front the more you have to worry about rubbing and ride-height. It won't matter though with 235. Worry about it with 255 on the front.

tlebovic wrote: ↑Fri Feb 28, 2025 3:08 pm but I went ahead and purchased a set of Michelin Pilot Sport All Season - which he also gave me a hard time about because 'A sports car shouldn't have a tread pattern that ugly'.

Form follows function. Your mechanic's a dork.

All season tires can be expected to have
- better wet traction
- better cold (<50°) traction
- far less warm up time to get maximum traction.

Ultra-high Performance (UHP) all-seasons tires can be expected to have 90+% of the warm traction of a comparable Summer tire.

For these reasons unless you are DE-ing, AX-ing, or exploring the last 5% of traction on public roads UHP all-seasons are typically a better choice than Summer-only tires.

This wasn't true 10 years ago. But it is now.

tlebovic wrote: ↑Fri Feb 28, 2025 3:08 pm Everything was fine for the 4 driving seasons they lasted - they wore out in the center on the rears after about 20k miles

If you're not wearing out the rears within 20k miles you need more lead in your foot.

But, tread wear should be even(-ish). The inside should have the most wear (due to camber) but the wear should be less and less (uniform distribution of wear with small slope) as you go to the outside. Wear in the middle means over-inflation. There's no reason to run more than 36 PSI on a 928 with a modern tire. (Indeed lower can be better but much homework is required and 36 is a totally safe starting point.)

tlebovic wrote: ↑Fri Feb 28, 2025 3:08 pm So what's the lists' opinion here? Go with the wider tire to take advantage of the 8" wheel?

Yes.

tlebovic wrote: ↑Fri Feb 28, 2025 3:08 pm Tire Rack does have Michelin Pilot Sport All Season in both sizes, along with PS2's in the smaller size.
For Bridgestone they have RE71's in both sizes but the wear rating is half of the Michelins so I'd be looking at another quick replacement.

Stick with UHP All-seasons:

Continental ExtremeContact DWS 06 Plus
Michelin Pilot Sport All Season 4
Yokohama ADVAN Sport A/S+
BFGoodrich g-Force COMP-2 A/S PLUS

Naturally, I agree with David (Worf). I have used the 8" front wheels with Michelin Pilot AS (some number here, up to 4 now) on 3 different street/highway cars ever since they first became available, and like that set up. Wish I could get the 8" Porsche Sport Design wheels (which I like the looks of on a GTS) in the proper offset of 70, but only available in low 50's.