718 GT4 wheels on a GTS 4.0?

[LiamH66]

As per title, I should have a track day coming up before my GT4 RS gets here, or at least before I've had a chance to run it in. I'm expecting my 981 GT4 to be sold by the time, so will most likely use my Cayman GTS 4.0.

I have a set of standard 718 GT4 wheels with PS Cup 2 on them, one track-day old, and I managed not to overheat them very much at all. So a good set of tyres that I can likely extract more value from...

GT4 tyres are all wider, wheel offsets evidently a little different, and rear rims are 11" rather than 10.5".

Does anyone know if it's worth trying the GT4 wheels and tyres on the GTS 4.0? Offsets only seem out of accepted range by a mm or so, but with the tyres being a bit wider, I'm wondering if the fronts might foul anything inside the arches.

Probably short of time to experiment, so if anyone has been through the exercise before, advice would be appreciated. I'll equally enjoy a day out on the PS4S's that came with the GTS, but I'm hoping to preserve them for less aggressive road miles.

Liam

[130R]

Based on what I have seen on rennlist, the fronts will be fine but the rears will not. The rear tyre sidewall could contact the suspension under cornering load so you would need spacers.

[TDT]

Its only one day... just do it on the PS4S - just don't to too many laps in a single session - to mitigate excessive overheating especially if its a hot day.

PS4S is the control tyre for many race series so will be fine for a single day.

[LiamH66]

Thanks both for very helpful replies.

@TDT, I'll be following your advice, and letting plenty of air out as they warm up too. I think I should've learnt my lessons on overheating tyres by staying out after they are already getting hot and pressures are getting into crazy rises. We'll see!

Liam

[JayK12]

The PS4S will be fine, 32 HOT they will stay pretty consistent.

[rawenghey]

JayK12 said:

The PS4S will be fine, 32 HOT they will stay pretty consistent.

Oh wow, as low as that? So 26ish leaving the pits?

[LiamH66]

rawenghey said:

Oh wow, as low as that? So 26ish leaving the pits?

Yes, definitely in that ballpark, and on a warm day you'll likely need to let a bit more out too.

On Cup 2 in the GT4 I'm generally aiming for 28 front / 30 rear hot on the track in hot weather, and looking at the tyres after the last one, they could still come down a pound or 2. Didn't let them cool down before putting more air in, but I'll bet the left rear would have been down to less than 20 psi cold, and the other 3 not much higher than 20.

Was at Silverstone International, so a lot of fairly fast corners, and you do notice how quickly heat gets put into the tyres as you find the limiting speed around the corner apex. If it sounds like a load of angry imps trying to hammer their way in through the wheel arches as the car slides, tyres are too hot and starting to shed some lumps of rubber. I'm starting to get a feel for when that's about to happen, rather than carrying on until it does.

Liam

[I Like Tea]

I have run 718 GT4 wheels on my 2.5T 718 GTS. Car was on PASM at the time. No problems at all.

[LiamH66]

I Like Tea said:

I have run 718 GT4 wheels on my 2.5T 718 GTS. Car was on PASM at the time. No problems at all.

Good to know, thank you @I Like Tea. Road or track use? Just wondering if the Rennlist suggestion of cornering loads is a potential risk, or something that actually happens.

Liam

[I Like Tea]

LiamH66 said:

I Like Tea said:

I have run 718 GT4 wheels on my 2.5T 718 GTS. Car was on PASM at the time. No problems at all.

Good to know, thank you @I Like Tea. Road or track use? Just wondering if the Rennlist suggestion of cornering loads is a potential risk, or something that actually happens.

Liam

Both road and track. I was running a slightly stiffer and shorter Eibach spring and Yokohama A052 in GT4 sizes.