The GT4 Tyre Thread - Page 3 - Boxster/Cayman - PistonHeads UK

Just wondered about experiences to date - what are people running, and the relative merits, or otherwise, of the various options? Mine arrived on Dunlop MXX Race - with conspicuously little initial tread. One track day at Silverstone GP and the fronts are pretty much gone (may have allowed pressures to get a bit high - 2.6 bar) despite only 3-4 lap runs on a cool day. Plan is to have two sets of wheels - one with road legal/track biased tyres (MPSC2? or MPSS?) with good wear rates, and a second set of pure road tyres for year round use ('N' spec with nice road driving characteristics). Any thoughts?

In my experience Cup 2s wear a little better but not massively so. I find the Cup 2 fronts can last two whole days...something strange about the front tyre wear rates on this car. I also believe the non N rated Cup 2s are much harder wearing than the N rated ones...but not sure whether overall grip is lower or not (in the non N spec). Interestingly over in the M3 world they are less impressed with the Cup 2s and believe they go off too quickly - probably a feature of the non N spec versions. I bumped into AP at Goodwood FOS and enquired about the high front tyre wear rates on the GT4 - he just looked down at me with the 'you amateur' look and said his test drivers had not reported anything like this. Was frankly a little disappointed with his inability to listen as most of my friends - many experienced trackers - are all reporting similar findings. Maybe its an amateur thing but then that is the target market!

I'm running the Dunlops and I really rate them, so much so I've just stuck another set on! Not sure why they have such a poor reputation on here, particularly how well they seem to perform on a track. My only issues with the Dunlops is the wear rate as mine lasted <4k miles (I don't think cup2's are much better) and also the price (Cup2's seem to be cheaper)

LaSource said: I bumped into AP at Goodwood FOS and enquired about the high front tyre wear rates on the GT4 - he just looked down at me with the 'you amateur' look and said his test drivers had not reported anything like this. Was frankly a little disappointed with his inability to listen as most of my friends - many experienced trackers - are all reporting similar findings. Maybe its an amateur thing but then that is the target market! I have to say I've not experienced this, but I have read that other have too... I found both the front and rear to have worn and pretty much worn at identical rates, first car I've ever experienced this with!

MPSS are very much a road tyre only. keep those for your road wheels if you're going to get 2 sets. as a all round tyre the cup2 is pretty good imo.... The gt4 seems remarkably hard on it's front tyres though so I'm not sure cup2s will last very much longer. Oddly enough I've got a set of N spec cup2s on another car and they haven't shown anything like the amount of wear (fused the front left tread marks after 1.5 days in the gt4, nothing even close to that in the other) despite broadly similar geometry (0 front toe, -1.75 front camber).

isaldiri said: MPSS are very much a road tyre only. keep those for your road wheels if you're going to get 2 sets. as a all round tyre the cup2 is pretty good imo.... The gt4 seems remarkably hard on it's front tyres though so I'm not sure cup2s will last very much longer. Oddly enough I've got a set of N spec cup2s on another car and they haven't shown anything like the amount of wear (fused the front left tread marks after 1.5 days in the gt4, nothing even close to that in the other) despite broadly similar geometry (0 front toe, -1.75 front camber). As I've posted before, I believe the difference could be that the GT4 front rim is a little narrow for the wide 245 section tyres and hence you get a motorbike like bulge in the middle of the tyre. This could also explain why the fronts wear in the middle of the tyre and not the edges first - almost regardless of pressures or camber settings.

Perhaps, in which case the fronts could be very pressure sensitive. The wear is quite unusual - through the lhs of the centre block on both fronts. Rears wore fairly consistently. Certainly these Dunlop fronts were barely road legal after just one track outing, and S.GP isn't particularly abrasive.

as can be seen fit what you like, people like cups people like Dunlops. I am in the cup 2 camp as I hate Dunlops. you will kill then on oem geo imo I run -2.2 and on 3k and track day they look ok still. AS the OP found Dunlops over heat like a ***** and one can never dial in a pressure Cups, you change the PSI twice and it's stable all day. Edited by Porsche911R on Tuesday 2nd August 15:01

LaSource said: As I've posted before, I believe the difference could be that the GT4 front rim is a little narrow for the wide 245 section tyres and hence you get a motorbike like bulge in the middle of the tyre. This could also explain why the fronts wear in the middle of the tyre and not the edges first - almost regardless of pressures or camber settings. yeah i remember you mentioned that, 8.5J on the gt4 vs most other cars running 9s on 245s if I recall correctly. Oddly enough though it was the tyre shoulders that got battered worse for me than the middle so quite the opposite of you...

I reckon GT4 is such a weapon I don't think the factory tyre choice will make a whole load of difference to the feel or performance of the car. That said I was hoping for the Mitchelins on my car and have the Dunlops which I really can't fault. If anything once they get very hot on track the car becomes even more characterful, I mean that as a complement to the tyre and car set up in so much as some tyres seem to go off and the car is no longer fun. The GT4 remains consistent and fun from what I've found so far. Testing continues The front tyre inner shoulder wear is odd, interesting thought on tyre width, I assumed it must have been temperature related.

flat6gallivant said: The front tyre inner shoulder wear is odd, interesting thought on tyre width, I assumed it must have been temperature related. ...slight update. Cup 2 fronts defo last no more than 2 track days ( or maybe even less!)...a day at Spa finished mine...and this is with shimmed cambered front axle. Speaking to RSR yesterday another explanation was suggested - GT4 caster setting. If the caster means the wheel is sliding at an angle through corners then the centre tread block could get more scrub (picture a std merc saloon front axle caster) Also wondering whether the spring rates are too soft ...maybe someone more knowledgeable about suspensions/steering can add something here.

if you go above the -2.2 I have, caster is an issue, so you need caster adjustment there after. I would try the DSC controller if you track the GT4 as that stops the roll and dive on hard brakes they are only £950 and would sell well 2nd hand and seem to work. you might not get faster laps with a DSC unit but you might have tyres which last a lot longer. http://www.dscsport.com/2016/06/21/randy-pobst-mar...

LaSource said: Also wondering whether the spring rates are too soft ...maybe someone more knowledgeable about suspensions/steering can add something here. is that not the nub of it all though, people want a more compliant road car that doesnt have 'fancy' tech so something has got to give? Up the spring rate and it becomes to harsh/average user wont enjoy the bumpy ride, make it softer and the average user enjoys it but at the expense of the track rat and the issues it may bring?

What is the stock gt4 spring rate?

Porsche911R said: as can be seen fit what you like, people like cups people like Dunlops. I am in the cup 2 camp as I hate Dunlops. you will kill then on oem geo imo I run -2.2 and on 3k and track day they look ok still. AS the OP found Dunlops over heat like a ***** and one can never dial in a pressure Cups, you change the PSI twice and it's stable all day. http://www.pistonheads.com/gassing/topic.asp?h=0&t=1140774&r=26073520&hm=15789&mid=15789#26073520

DeaconFrost said: What is the stock gt4 spring rate? Front 45N/mm Rear 80N/mm If i remember correctly....

Slippydiff said: http://www.pistonheads.com/gassing/topic.asp?h=0&a... You gone back into mad stalker mode ? Wtf ! I was about the 1st person to try these, they won a few tests, and I like to try the best products, this is a 2012 thread I hated the tyres and told people why and I thrown them away not even half worn. ,

isaldiri said: Front 45N/mm Rear 80N/mm If i remember correctly.... That's surprisingly soft. Interesting.

The current Porsche 'approved' tyres for the GT4 are: - Michelin Pilot Sport Cup 2 - Dunlop Sport Maxx Race Both, F. 245/35 ZR20 N0 and R. 295/30 ZR20 N0 PEC use the Michelins on their GT4s (not sure if this is contractual) with standard set up and pressures. Wear rates vary, depending on weather conditions and driver skills (apparently most PEC customers are quite conservative on track). There is an 'approved' Winter option - Michelin XTLT Pilot Alpin 4 N0 (F. 235/35 R20 and R. 275/30 R20 N0). So, there is some size allowances on the 8.5" and 11" rims. Personally I'd prefer to have two sets of wheels and tyres - 'track' probably MPSC2s, but unsure what 'road' tyres. Are there any compatible 'N-spec' sizes in, ideally, Michelin Pilot Super Sports or Goodyear F1 Eagle ASs? Edited by Geneve on Monday 29th August 11:22

Looks like there is an N-rated PZero in the right sizes for a more road tyre. Have just replaced the front Cup2s on my car after three track days and 6 laps of the Ring. As others have said, wear pattern is a bit odd with the outside shoulder of the left front worn and the tread block inside the outer grove chamfered down below the wear bars. Rigth front tyre would probably do another day. Rears more evenly worn and still with about 4.5mm tread left. I've put more Cup2s on, but price is a bit alarming!

I'm on the my second set of Dunlop which I rate them quite well for road/track, seem to wear extremely consistently on my car. The only major downside I've found is they are more expensive that Cup2's. I do however now have a set of Trofeo R for track work...looking forward to seeing how they compare, just need to source another set of wheels to save the hassle of changing tyres.

nudgerwilliams said: Looks like there is an N-rated PZero in the right sizes for a more road tyre. Not keen on Pirellis - what are the other N-spec tyres in similar sizes? Michelin Super Sports? nudgerwilliams said: Have just replaced the front Cup2s on my car after three track days and 6 laps of the Ring. As others have said, wear pattern is a bit odd with the outside shoulder of the left front worn and the tread block inside the outer grove chamfered down below the wear bars. Rigth front tyre would probably do another day. Rears more evenly worn and still with about 4.5mm tread left. I've put more Cup2s on, but price is a bit alarming! That's my experience with the Dunlops - light/even wear on the rears, but more rapid, and slightly unusual, wear on the fronts.

On the BlackCircles website, the only N-rated tyres they have in the right size are the Cup2, the Dunlop SportMaxx and the PZero. Lots of choice in the right size inluding Pilot SuperSports. The budget own-brand choice is a mere £64 each on the front - presumably those would be good for practicing skids!

Porsche911R said: You gone back into mad stalker mode ? Wtf ! Don't flatter yourself David, I was never in "mad stalker mode", on the contrary, the fact of the matter was you couldn't deal with being quoted and/or called out by numerous contributors on here. The sooner you realise this is a public forum with all that entails, the better, ergo if you don't want me to read and respond to your posts, don't post on here. Simple. ;-) Back on topic. I recalled you raved about the Dunlops (inbetween bemoaning Porsche and their great N rated "rip off" and getting your facts about the PS2's wrong...) so I thought I'd check back to see if the only thing consistent about the stuff you post on here was it's inconsistency.... Porsche911R said: I was about the 1st person to try these, they won a few tests, and I like to try the best products, this is a 2012 thread I hated the tyres and told people why and I thrown them away not even half worn. , Just for the record, it's threw ;-) But good for you for testing them for everyone else and deciding they're not worthy, a bit like snow foam and pretty much every iteration of the GT3 Porsche has ever built (Gen 2 997 GT3 apart obviously) This forum is SO lucky to have someone as unbiased as yourself who's happy to vet products and cars on our behalf, I really don't know what we'd do without you Edited by Slippydiff on Thursday 1st September 13:58

isaldiri said: Front 45N/mm Rear 80N/mm If i remember correctly.... surely these figures are wrong.......

Beedub said: surely these figures are wrong....... As far as I can remember they are the correct numbers as per some launch reviews. Front has the same rate as the 991 gt3 but less rear spring rate. I'd google to be sure if I wasn't on the mobile but think they are right... . Why would you think the numbers have to be wrong out of interest?

Dunlop SMRs now replaced with Michelin PSC2s(at 2k mls ) First subjective impressions are of a better road and track tyre, and hopefully longer life. Did notice a bit more road noise on some m/way surfaces. Still trying to work out which set of standard N-spec road tyres to put on my second set of wheels. Would prefer Goodyear Eagle F1 AS2s, but can't find anyone who can clarify if the 265/35s will fit on the 11" rears. They certainly fit on the Spyder's 10.5" rears?

Approved sizes for Cayman GT4: Summer FA: 245/35 ZR 20 (91Y) RA: 295/30 ZR 20 (101Y) XL FA: 8.5 J x 20 H2, RO 61 RA: 11 J x 20 H2, RO 50 Winter FA: 235/35 R 20 92V M+S RA: 275/30 R 20 97V M+S FA: 8.5J x 20 H2, RO 57 RA: 10 J x 20 H2, RO 50 FA: 245/35 R 20 91V M+S RA: 295/30 R 20 97V M+S FA: 8.5J x 20 H2, RO 61 RA: 11 J x 20 H2, RO 50 I would think the 265's would lend it an air of the VW stretch and poke trend...

Pope said: I would think the 265's would lend it an air of the VW stretch and poke trend... Thanks Jon What did you mean by that? Fitting slightly 'over' or 'under' sized tyres is not unusual, there's usually a degree of flexibility. Just be nice to have an expert opinion on the subject. Pirelli do the exact sizes, but really not keen on them, and they are noisy. Would much prefer the GYs.

Geneve said: Thanks Jon What did you mean by that? Fitting slightly 'over' or 'under' sized tyres is not unusual, there's usually a degree of flexibility. Just be nice to have an expert opinion on the subject. Pirelli do the exact sizes, but really not keen on them, and they are noisy. Would much prefer the GYs. 265 is quite a bit smaller than the 295 stock size!

Ok, slight exaggeration maybe :

Geneve said: One track day at Silverstone GP and the fronts are pretty much gone IMO that's the inevitable consequence of pushing round a circuit in a heavy road car. I'm a big fan of Michelin but the prospect of destroying an expensive set of tyres in one trackday wouldn't fill me with any joy at all.

The latest missive from Evo on tyres tested is interesting. http://www.evo.co.uk/features/18309/the-best-tyres... Different sizes and car, but does give some indication of the priorities of the various manufacturers - and shows (if you didn't know already) that there are tradeoffs between dry and wet road grip, braking and sideways adhesion, ride and noise - and you can't have everything.

I agree, the Continentals looked good in 19" ... PSS's good in the dry ... ! I use them as wets over PSC2's ... go figure

OK, now sorted. Two sets of OE wheels and two sets of tyres. The disappointing, short lived, Dunlops now replaced with Michelin MPCS2s for road/track and, aside from a tad more road noise, a better tyre IMO and likely to be much more durable. Second set (year round road use), Goodyear Eagle F1 AS2s, fitted following liaison with Goodyear Technical - 235/35R20 N0 and 275/35R20 M2. Ran them 'back to back' and very pleased. GYs quieter by several dB, especially on UK m/ways, and a noticeably more compliant feel, rounding out sharp bumps. Entirely subjective, but very sweet road handling, wet or dry. And good value - £800 all inc at Protyre.

Anoer owned of Dunlops disappointed, keeps happening :-)

Can we run N1?

TDT said: Can we run N1? you can run any tyre you wish N spec means nothing and has not been tested on any older car.

hi All, just about to buy a full set of front and rear tyres for my 981 GT4. On Black Circles I'm being presented with MPSC2 N1 front and rear-is this correct? Thanks in advance, Gavin

gavin wot said: hi All, just about to buy a full set of front and rear tyres for my 981 GT4. On Black Circles I'm being presented with MPSC2 N1 front and rear-is this correct? Thanks in advance, Gavin Yep correct.

Cheers