CanAutM3

My take is that it is the combo of tire, rim width and offset that is of issue.

While the offset and wheel width combination does position the wheel face slightly more outboard, it is still the offset determines the position of the tire relative to the fender, which puts it 3mm more inboard.

The PS4S tread is quite narrower than the GT3’s stock PSC2, which makes it fill the wheel well less than stock, particularly so if you have the AML spec.

The 0.5” wider rims stretch the narrower tire more, which will accentuate the “short sidewall” look.

Best option here IMO is to either stick with the stock GT3 PSC2 or even better go with slightly wider 991.2 GT3RS PSC2 (265/35R20-325/30R21) N2 spec which are optimally designed for 9” and 12.5” wide wheels.

division

The offset is the issue.

J Irwan

The offset is not the issue. (I've done the calculation above.Please see the offset table).

I always love how beefy the Michelin Cup 2 tires looks on Stock GT3 rim.

If OP were to have the stock Michelin Cup 2 - 315/30/21 in N-Spec installed on the HRE, we wont be having this conversation.

The stock GT3 offset is perfect as it is, and 3.3mm more outward on the HRE would have been nothing and would look largely the same appearance (in thickness or sidewall profile) as stock.


I am sure (this my assumption) that OP is not looking for stretched look, if you like the "stretch" looks then yes you go with even lower offset in order to fill the fender gap.

division

Calculations or not, if your wheel/tire isn't "sticking out" where you want it, the offset is wrong. This exact same wheel/tire combo on the exact same rim needs to be moved outwards, and that's a function of offset in this situation.

The "stretched" look is a function of a too-wide rim and a narrower-than-it-should-be tire. Putting a wider tire on the rim will give you the "Speed Buggy" look (exaggerated, of course) , which isn't going to solve the problem with this tire/wheel sticking out like it should visually. If you put spacers on the exact same current setup, it'll push the wheel out where OP wants it, but that just means the wrong offset is being run.

The issue is the offset.

edit: I'm talking about "poke" (as the Jeep guys call it), not tire gap. Also, offset or backspacing... take your pick 'cause they're the same things.

CanAutM3

While not the most significant contributor, the 3mm larger offset will position the tire tread 3mm more inboard regardless of the wheel width. The larger offset exacerbates the visual effect of the narrower treaded tire.

J Irwan

the offset is 3mm higher (12.5x21 ET48) but the wheel width is .5” wider the net-net is the whole wheel is 3.3mm more outward compare to stock 12x21 et45


how wheel sticking out can also be manipulated further by playing with camber.

the baseline is the OEM GT3 wheel (which you can see its already pretty damn good, stock is pretty flushed). The new HRE wheel is only 3.3mm stickout outward.

are you saying the stock GT3 wheel has wrong offset ?

as @AlterZgo if you want to get the wheel more outward you definitely dont want lower the car further. Lowering the car further will create more negative camber. more negative camber means the top of of the wheels will be pushed in more (similar effect of going with higher offset)

Shogunade

I really cant wait to see how HRE is gonna handle this.

division

I'm saying that if the OP wants the wheel to sit further out in the current setup, he needs a different offset.

Sure, add some positive camber, and the top of the tire might be where he wants it, but then his suspension geometry is now different. Put on different tires, and he might be where he wants it. If you use the exact same wheel/tire combo that he has now and he wants it out further, he needs either spacers or a different offset.

Personally, I'd run the OEM tires and take it from there. You know you have the correct tire for the car, and if something is now off (visually, as is the case here), it's going to be wheel related. Until then, we're trying to figure out if the tires are wrong, the wheel offset is wrong, or if the tire/wheel combination wheel offset is wrong. You gotta figure out what you're trying to accomplish, and apparently calling HRE and saying "Hey, I need some Michelins in this size for my GT3 and some wheels that'll fit" isn't the best way to go about it.

Again, this doesn't address the tire gap (if that's an issue, looks good to me), just the poke.

CanAutM3

Again: the tire tread position relative to the fender is solely dependent on the wheel offset irrespective of the wheel width.

While your calculations are accurate for the wheel face position (not the whole wheel as you state), they are not for the tire’s tread position. A mounted tire is always centered on the wheel centerline. Moving the wheel centerline inboard will move the tire tread inboard by an equal amount.

J Irwan

At least we agree that best course of action likely use stock size N-spec cup 2 that came with the car from the factory.

the gt3 oem wheels is rhe baseline, if the new wheels looks awkward then we know its the wheels. (This is the easiest path without getting to technical in analyzing which tires will looks good with the new wheels, or if the new wheel is built with wrong offset)

J Irwan

yes there is an art about choosing how the sidewall shape looks (straight, or more curve inward). if you looks at guntherwerks/singer car you can tell they choose carefully, i suspect they probably choose how they want the sidewall to visually looks, then decide how wide they want the tire (and what brand) then they build the wheel with custom width and offset.


Regardless offset, the 12” wide tire with 315/30/21 may have straigh vertical sidewall, while the same tire with 12.5” wide maybe curving inward.

even if thats the case i’ve seen the effect is minimal, but base on the OP pictures the tire is severely too narrow, so the sidewall is visually collapse (tire looks thinner from a distance, thus create more void as the larger fender gap).

division

Completely agree. Slap your old tires on these rims and see what it looks like. Might cost you a couple hundred bucks for the dismounting/mounting, but such is life. Until then, we can just sit here and argue and double check each other's math.

CanAutM3

Pretty much what I said in post #31

J Irwan

@richiele23 I missed this clue.

your friend has the same exact wheel but the tire looks normal. Which tire does your friend have ? Does your friend run stock Michelin Cup2 on the same wheels ?

J Irwan

and I found a GT3 with stock rim running stock size Porsche-spec Goodyear Eagle F1 (N0) https://bringatrailer.com/listing/20...t3-touring-89/
the key here is you need to run Porsche-spec tires to get the proper tire looks.