GT4 Tyres
Author
Discussion

trowelhead

Original Poster:

1,867 posts

145 months

Wednesday 28th June 2017
quotequote all
So... daily driving my GT4. Back end just came out on a roundabout at low speed in the wet

What are the options for a more suitable daily driving Road tyre? 😀

Taffy66

5,964 posts

126 months

Wednesday 28th June 2017
quotequote all

Dunlops or Michelins..? Either way the GT4 is not very good in the wet..

av185

20,464 posts

151 months

Wednesday 28th June 2017
quotequote all
Dunlops on mine.

Probably as good as the 991 GT3 Michelins in the wet...for road use.

Porsche911R

21,146 posts

289 months

Wednesday 28th June 2017
quotequote all
Dunlops are much worst than cup 2 esp if cold, also harder to get heat into them.
I binned mine for cup 2 it's a much better tyre.
Dunlops also a st track tyre very unstable.

As for rear end step out, that's a right foot issue, the cars set up to under steer, but a heavy right foot will step out the rear post apex. I call it fun ;-) either that or your rear wheels are pointing in different directions.

I have done Evo triangle at daft speeds in the wet on cup 2’s , butt clenching mine you.

If you want a road tyre as a cup 2 is a daft all year round road tyre, try PS4S

I run 2 cars on cup 2 and 2 on PS4S , 2 of the best tyres imo.
The PS4S is the new king of road tyres if you use the car when it rains.

The PSS might have the slightly better feel in the dry, the PS4S is a far better damp running tyre so wins.

Dunlops I would rather just throw them away, and I did 1.2k worth and last week chucked a brand new set of P Zero

Car are to expensive to run st like those 2 tyres imo I am shocked people put up with them both. No other big super car manufacture fits either of them to their high end stuff.

GT4P

5,804 posts

209 months

Wednesday 28th June 2017
quotequote all
I did my pec day on a very wet cold day in October 2015 the car had michelin cup2s which were excellent! I am no driving god but the car was easy to catch if it did step out at the rear.
Could have been some oil on the roundabout which would have caught you out no matter what tyre if you approached at speed.
Although most of my gt4 use is dry use even on the odd occasion when I have used my car on very cold damp days I have never found the tyres a problem

Edited by GT4P on Wednesday 28th June 22:17

nudgerwilliams

247 posts

205 months

Wednesday 28th June 2017
quotequote all
trowelhead said:
So... daily driving my GT4. Back end just came out on a roundabout at low speed in the wet

What are the options for a more suitable daily driving Road tyre? ??
Might have been diesel on the roundabout, in which case same thing may have happened with other tyres.

Cup2s on mine, which have been fine in the wet, except where there has been standing water around when I have slowed right down.


ClarkeyDiem

17 posts

122 months

Wednesday 28th June 2017
quotequote all
Trowelhead, I have a set of nearly new N rated Pirelli P Zeros if you are interested? I put Cup2 on as soon as I bought my GT4. Previous owner went for Pirellis as he thought them the best "all round" tyre...

Sandy59

2,730 posts

235 months

Thursday 29th June 2017
quotequote all
nudgerwilliams said:
Might have been diesel on the roundabout, in which case same thing may have happened with other tyres.

Cup2s on mine, which have been fine in the wet, except where there has been standing water around when I have slowed right down.
+1

Porsche911R

21,146 posts

289 months

Thursday 29th June 2017
quotequote all
If there were diesel on the roundabout you would have noticed a heap of understeer in the 1st place or feel it though the steering wheel even with EPS !

this is why bikes low side crash on diesel roundabouts the front wheel goes though1st !

Edited by Porsche911R on Thursday 29th June 08:49

chrisABP

1,117 posts

172 months

Thursday 29th June 2017
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My GT4 was a late 2016 car and unfortunately came with the Dunlop tyres.....Whilst they work well once up to temperature on a dry surface they are pretty crap compared with the Cup 2's (which I had on my 997 GTS) in cold or any type of damp conditions. I also used the Pilot Supersport on my BMW 1M and found those to be a great all round tyre but don't think they are available N rated for the GT4.
I am seriously considering swapping out my Dunlop for a set of Michelin Pilot Cup 2's as I know 100% they will work better in most conditions. Its just the £££ stopping me after just 1,600 miles wear on the Dunlops....

Porsche911R

21,146 posts

289 months

Thursday 29th June 2017
quotequote all
chrisABP said:
My GT4 was a late 2016 car and unfortunately came with the Dunlop tyres.....Whilst they work well once up to temperature on a dry surface they are pretty crap compared with the Cup 2's (which I had on my 997 GTS) in cold or any type of damp conditions. I also used the Pilot Supersport on my BMW 1M and found those to be a great all round tyre but don't think they are available N rated for the GT4.
I am seriously considering swapping out my Dunlop for a set of Michelin Pilot Cup 2's as I know 100% they will work better in most conditions. Its just the £££ stopping me after just 1,600 miles wear on the Dunlops....
Just swap them out today and drive the car with nice boots on :-) thank me later for forcing the issue. it's not like you are going to pay full price :-)

pete.g

1,531 posts

230 months

Thursday 29th June 2017
quotequote all
Porsche911R said:
If there were diesel on the roundabout you would have noticed a heap of understeer in the 1st place or feel it though the steering wheel even with EPS !

this is why bikes low side crash on diesel roundabouts the front wheel goes though1st !

Edited by Porsche911R on Thursday 29th June 08:49
You are assuming that the front wheels and the rear wheels have the same loci as a car turns a corner.

They don't - it is possible for a rear wheel to hit a patch of diesel that a front wheel has not passed over.

This is most easily observed in longer wheelbase vehicles - look at a van turning left, if the driver takes the corner with the front left wheel tight to the kerb, the rear left will mount the kerb as it has a different locus.

With motorcycles the loci are more contingent and this is why they are so susceptible to issues with diesel spills.




Edited by pete.g on Thursday 29th June 09:39

Geneve

3,999 posts

243 months

Thursday 29th June 2017
quotequote all
I have a second set of GT4 wheels running Goodyear Eagle F1s 275/35 Rears and 235/35 Fronts, These are for road use and are noticeably quieter and more compliant and excellent in the wet. Goodyear Technical advised me, although only the fronts are N spec.

Porsche911R

21,146 posts

289 months

Thursday 29th June 2017
quotequote all
Geneve said:
I have a second set of GT4 wheels running Goodyear Eagle F1s 275/35 Rears and 235/35 Fronts, These are for road use and are noticeably quieter and more compliant and excellent in the wet. Goodyear Technical advised me, although only the fronts are N spec.
So a Goodyear tech said mix compounds and fit a 275 on a 11" rim ! plus you have increased the rear dia by 16mm (>2.34%)but the front reduced by 6mm (0.88)

Odd advice


Cblair246

200 posts

146 months

Thursday 29th June 2017
quotequote all
Cup 2 is a great ultra performance tyre but has a reasonably narrow operating window i find. Below 10 deg and wet I think it starts to get a bit of a liability and you get those rear end moments which aren't nice. Unfortunately, in north Scotland it's over 90% of the year for those conditions! That's the reason I will be changing to the MPS4S most likely.

Is the MPS4S N rated?

Porsche911R

21,146 posts

289 months

Thursday 29th June 2017
quotequote all
Cblair246 said:
Cup 2 is a great ultra performance tyre but has a reasonably narrow operating window i find. Below 10 deg and wet I think it starts to get a bit of a liability and you get those rear end moments which aren't nice. Unfortunately, in north Scotland it's over 90% of the year for those conditions! That's the reason I will be changing to the MPS4S most likely.

Is the MPS4S N rated?
the PS4S is not N rated.

pete.g

1,531 posts

230 months

Thursday 29th June 2017
quotequote all
Porsche911R said:
So a Goodyear tech said mix compounds and fit a 275 on a 11" rim ! plus you have increased the rear dia by 16mm (>2.34%)but the front reduced by 6mm (0.88)

Odd advice
Your calculations are wrong: the effect is to increase the diameter by 15.5 at the front and 17.5 at the rear.

The radius, which determines ride height is therefore 7.75 at the front and 8.75 at the rear - or 1mm difference, which as the rears will wear more quickly than the fronts, is negligible.

As to the compounds, only Goodyear would really know, which is why asking their technician was a good idea.

Porsche911R

21,146 posts

289 months

Thursday 29th June 2017
quotequote all
pete.g said:
Your calculations are wrong: the effect is to increase the diameter by 15.5 at the front and 17.5 at the rear.

The radius, which determines ride height is therefore 7.75 at the front and 8.75 at the rear - or 1mm difference, which as the rears will wear more quickly than the fronts, is negligible.

As to the compounds, only Goodyear would really know, which is why asking their technician was a good idea.
I'll look later , it looked wrong to me on 1st look on all accounts. stock is 295/30/20 and 245/35/20 so both circa 84 circumference
Geneve stated GT4 wheels so now have 275/35/20 and 235/35/20

correct ?

if so the rears are 2.2% bigger now and a 275 is not right for a 11" rim ! now 86.6in circumference so sits 8mm higher

The front now are 1.4% smaller. 83.2in which puts it 3.5mm lower

what am I missing ? or what are you missing ;-)



Edited by Porsche911R on Friday 30th June 09:00

Geneve

3,999 posts

243 months

Thursday 29th June 2017
quotequote all
Thanks Pete.

With most of my Porsches I keep everything as per spec, but Goodyear were very helpful. The tread footprint is very slightly narrower than the standard Dunlops/Michelins and works very nicely on road.

However, the Michelin PS4S might be a worthy option, although, again, not 'N' spec - but these may start to become avilable this autumn.


Porsche911R

21,146 posts

289 months

Thursday 29th June 2017
quotequote all
Geneve said:
Thanks Pete.

With most of my Porsches I keep everything as per spec, but Goodyear were very helpful. The tread footprint is very slightly narrower than the standard Dunlops/Michelins and works very nicely on road.

However, the Michelin PS4S might be a worthy option, although, again, not 'N' spec - but these may start to become avilable this autumn.
unless I am having a really bad day lol does happen, Pete and the Goodyear Tech seems well off !!!

are you sure they are the tyre sizes you have quoted on stock GT4 wheels ? I think you have posted wrong and you have in fact a 275/30/20 rear and not as you quote a 275/35/20.

That would add up perfect.

I am 1st to put my hands up as Goodyear should know what to fit lol but my maths are not working for me, or you have posted an incorrect rear tyre size.



Edited by Porsche911R on Thursday 29th June 15:14