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are there tires besides the Michelin Pilot Sport Cup 2s that, in a 305 width on a 12in wide rim, has a sidewall
that doesn’t bulge outwards from the tread to the rim? 325 sections might fix this but there really aren’t any choices. 335s seem too big.
305 on 12 is conservative , 305 is used on 11. Was that factory? The factory tries to make all around - most usable and efficient choices. And they do research and development to decide which tire,wheel will cover the spectrum of use & drivers for that car.
That being said, if you look at all hi end cars, you never see any mfg sending out tires that bubble/bulge out over a wheel. It is usually obvious that you have the wrong tire when you see that. So if I walked by your car and noticed tires bulging out I would say, thats the wrong size for that wheel. If you mount different tires and are able to see they look flush, you know you have the right tire, if it bulges, its too big. If youre a 'tuner' You have tires way,way too narrow on a wide wheel.
305 on 12 is conservative , 305 is used on 11. Was that factory? The factory tries to make all around - most usable and efficient choices. And they do research and development to decide which tire,wheel will cover the spectrum of use & drivers for that car.
That being said, if you look at all hi end cars, you never see any mfg sending out tires that bubble/bulge out over a wheel. It is usually obvious that you have the wrong tire when you see that. So if I walked by your car and noticed tires bulging out I would say, thats the wrong size for that wheel. If you mount different tires and are able to see they look flush, you know you have the right tire, if it bulges, its too big. If youre a 'tuner' You have tires way,way too narrow on a wide wheel.
305s on the rear 12" wheels are factory. This has been factory on the entire 991 generation of the GT3. The Carrera and Turbo wheels were 11.5" at one point, also with 305s.
As I was mentioning in my original post, the question here isn't whether or not these are the correctly-sized tires for these wheels (they are, by the way). What I'm looking for is what other tires out there have sidewalls that don't have the sidewall "bulge" (as you're describing). 305s in these Michelin Pilot Sport 4S *do* have it, while the 305s in the Sport Cup 2s *don't*. Look at the GT3 rear wheels and you'll see the sidewalls have very little to no "bulge" to them, even at 305 widths on a 12" rim.
A wider tire will make the sidewalls more perpendicular or straight up and down (flush?), but the car will probably handle better the way it is. Stretching the bead outward like it is (to a point) enhances tread stability. That said, the recommended wheel width for a 305/30-20 tire is 10.5-11.5”, so with 12s, you could probably go up in width to 315 or 325mm, but you’d have to find the right aspect ratio to keep the overall diameter close to stock or else the stability controls or ABS might get thrown off.
Interestingly I believe Pirelli Trofeo R's have a wider 'foot print' but are still 305/30. Tyres do differ, Michelin's are usually wider than some other brands. As Need4S has stated the manufacturer recommends 11.5 " maxiumum. Porsche have always used larger rims. The back of my old M5 has 295/30 x 20 on 10x20, so very underwheeled in comparison. You could fit 325/30 20 but you will, increase the radius by 6mm which might alter some of the suspension design computing (But I very much doubt it for 6mm)
01-22-2018, 04:36 PM
Tires with a flush sidewall
