THE Tire Thread

[Fubar]

Just the facts ma'am, just the facts.

Please post brand and sizes that you are using (besides the OEMs).

I'm just trying to make a thread that is easy to use for those looking to get something different. Here is what we have so far:

OEM: (Side Height) change from stock
Goodyear
F1 SuperCar
235/45-18 Front (105.75) 0%
315/40-19 Rear (126.00) 0%

Non-OEM:
Michelin
Polit Sport PS2
Sport Cup
245/40-18 Front (85.75) -18.91%
345/30-19 Rear (103.00)-18.25%

Bridgestone
RE050A
RE050A Pole Position
265/35-18 Front (92.75) -13.00%
265/40-18 Front (106.00) +0.23%
255/40-18 Front (102.00) -3.54%

RE050A Scuderia
345/35-19 Rear (120.75) -4.17%

Hoosier
R6
245/45-18 Front (110.25) +4.25%
315/40-19 Rear (126.00) 0%

Pirelli
Pirelli PZero Corsa System * couldn't find a link for the corsa system
235/40-18 Front (94.00) -11.11%
345/35/19 Rear (120.75) -4.17%

*it goes without saying that one should always use caution when deviating from manufacturers original equipment.

 

[kmillen]

We are using O.E. BBS wheels with Michelin Pilot Sport PS 2

Front- 245/40ZR18
Rear- 345/30ZR19

Here is a link to the tires.

http://www.michelinman.com/tires/ultra-high-performance-sport/pilot-sport-ps2/

These sizes were recommended by the Michelin engineers. The rear tires are a little bit shorter and two inches wider than factory. We have one hard track day at Fontana on one set and we had no issues with rubbing. Also, even though the tires are wider we found that they fit nicely behind the fender.

At this time we only have one, 3 session track day on the tires and a few local around town trips. They seem to be a great tire and offer superb traction. One thing we noticed is that the shorter tire height definitely required some fine tuning of the suspension when tracking the car. This was easily adjusted through the Penske's.

We will have more information on the tires performance soon. The car is now on its way to New Zealand for the Targa Rally so it will be a great test of the tires.

 

[kmillen]

On a side note, if you aren't too concerned with treadwear and your only concerned with performance, I would recommend the Michelin Sport Cup. This is the same tire that comes standard on the Viper ACR's and it is an amazing tire. Incredible grip and good performance on the street. However, they don't last long.

http://www.michelinman.com/tires/ultra-high-performance-sport/pilot-sport-cup/

 

[SYCO GT]

Bridgestone RE050A
265/40R18

Bridgestone RE050A Scuderia
345/35R19

 

[Kingman]

Bridgestone RE050A Pole Position
265/35R18

Bridgestone RE050A Scuderia
345/35ZR19

 

[kmillen]

My calculations show that this combination changes the rake by 1.16" (nose up of course). How did you address this condition without negatively effecting performance or ride comfort?

We have the Penske's on our car so we were able to dial in the ride height. Here is a picture of the car prior to be loaded into the shipping container for the rally. To be 100% honest, I'm not quite sure how the car would sit with factory shocks.

http://i252.photobucket.com/albums/hh17/stillen75/FordGTprep2008009.jpg


By the way Fubar, I was just thinking about it and want to clarify that we are running the stock/aftermarket BBS wheels on our car. I'm not sure if you mean the factory 6 spokes or both options when you say O.E.

 

[SYCO GT]

Syco GT, HHGT and I all have the same size brand tires and I think all three of us are very happy.

Here they are on the rack, before they went on...

It was important for me personally to attempt to maintain a similar overall diameter front and rear to the stock tire diameter.

 

[Fubar]

I just changed from stock to these tires:

265/40ZR18 Bridgestone Potenza RE050A N1 (Porsche) IN STOCK 2 $294.00 $588.00
345/35ZR19 Bridgestone Potenza RE050A Scuderia IN STOCK 2 $335.00 $670.00

I do like the Bridgestones better. The cars feels heavier, more planted on the road. I will admit that it feels a bit strange... one of the more notable characteristics of the GT (to me) was it's nimble presence beneath your fingertips. I will no longer feel comfortable driving with two fingers on the steering wheel. So there are some sacrifices in diving with these tires but the gains with regard to traction are undeniable. I can tell the fronts have a much firmer grip on the road.

 

[John B]

Pirelli PZero Corsa System
F 235/40-18
R 345/35/19

Comparable to Hoosier R6's on track, way superior to Goodyears.
Better than Hoosiers and Goodyears on street.
Rears are bordering on too wide for wheel but ok with higher pressures. Dont drop them below 29.

 

[Pete S.]

Hoosier R6 as track tires with completely dry and warm conditions.

Goodyears as track tires with anything less than dry conditions and as daily street tires.

20,000 plus miles and counting.

Pete S.

Goodyears on the track:

 

[rick430]

tire change

Just put the Bridgestones on but instead of the 265 in front I opted to go 1 size smaller to 255/40 18. Read the posts regarding the lack of "nimbleness" after going with the 265 tire on the front. Pleased to announce that the car still feels light and nimble but "planted" all the time.Only drawback is the 255 is a W rated tire.

 

[Cyclenirvana]

To add to Fubar's very informative post: In our quest for the best alternatives to Goodyears and something with more grooves than the Hoosiers, wanted to post some data on the current tire selections and get some ideas about how this would theoretically (or realistically) affect handling:

Used the following link to obtain this data:
http://www.net-comber.com/tirecalc.html

Front , Dia. (in) , Rear , Dia. (in)

Goodyear 235/45/ZR18 , 26.327 , 315/40/ZR19 , 28.921

Hoosier R6 245/40/ZR18 , 25.717 , 315/40/ZR19 , 28.921
Ground clearance of front -0.305 inches. Rear unchanged.
Actual speed of front tire when speedometer reads 65 mph is 63.493.
Rear tire is unchanged.

Bridgestone 265/40/ZR18 , 26.346 , 345/35/ZR19 , 28.508
Potenza RE050A Scuderia (rear)
Ground clearance of front end +0.01 inches and rear by -0.207 inches.
Actual speed of front when speedometer reads 65 mph is 65.049.
Actual speed of rear when speedometer reads 65 mph is 64.071.

Pirelli Zero 245/35/ZR18 , 24.752 , 345/35/ZR19 , 28.508
Corsa System
Ground clearance of front end -0.787 inches and rear -0.207 inches.
Actual speed of front when speedometer reads 65 mph is 61.112.
Actual speed of rear when speedometer reads 65 mph is 64.071.

Pirelli Zero Corsa system also comes in a 235/40/ZR18 tire, 25.402 dia., which changes ground clearance in front -0.463 inches. Also speed of front when speedometer reads 65 mph is 62.716.

Michelin Pilot 245/40/ZR18 , 25.717 , 345/30/ZR19 , 27.150
Sport PS2
Ground clearance of front -0.305 inches but rear ground clearance -0.886 inches.
Actual speed of front tire when speedometer reads 65 mph is 63.493.
Actual speed of rear tire when speedometer reads 65 mph is 61.018

Now here are my questions:
1) More desirable to have the front end slightly lower than the rear? If this is the case the Hoosiers and Pirellis would be most desirable. The Bridgestones and especially the Michelins appear to raise the front end of the car. I assume this is why Stillen had to adjust their Penske's...but for those of us who do not have Penske's????
2) Speed sensors located in all 4 tires? rear vs. front?
3) Any problems with these combinations and our ABS system? previous posts seem to mention this as a potential problem.
4) Dave, any high speed runs on tires other than Goodyears or Hoosiers? If so, was the ride height adjusted?

This is probably extreme overkill but I think most of us are still wrestling with this issue.

 

[kmillen]

Review for Michelin PS2's: Used during 2008 New Zealand Targa Rally

First off let me start by saying that I am not a distributor for Michelin so the following review will be completely unbiased. I just want to tell everyone about our experiences with the PS2's on the rally and explain what we think of them.

To put it simply, we were VERY impressed with these tires. When we initially received the tires we were a little bit concerned that they might not have as much grip as we would like. They appear to have a lot of tread and they aren't what I would normally refer to as a soft compound. We were trying to decide whether we should go with the Michelin PS2's or the Sport Cup's. Michelin Sport Cup's are the same tires used on the new Viper ACR's and Steve had some experiences with them when testing the ACR for Road and Track. We would love to have used the Sport Cup's but our concern was that they would be too soft and not hold up for the entire week. So, we decided to stick with the PS2's.

After every stage we would inspect the tires to make sure they were holding up well and check to see if there were any issues arising. Every time we checked the rubber we found that it became very soft after it was warm. However, it didn't appear to be wearing out very quickly. We ended up having a half day in the rain and the wet weather performance was fantastic. The more time we spent on the tires the more confidence we gained in their performance. Unlike the factory Goodyear's the tires didn't get warm and greasy. They got warm and grippy! It was perfect!

On the last day we decided to change the rear tires. The ONLY reason for this was becuase it began to rain extremely hard and Steve just didn't want to take any unnecessary risks. We decided to put on some new rear tires to make sure that we had as much rear grip as possible. The last day of competition saw hurricane force winds and terrential downpours. Part of the rally was held on the peninsula around Wellington. The final stage of the rally was canceled due to ocean waves splashing on to the roads of the stage. Even in these conditions Steve felt confident in the car and pushed her hard. In some stages he was able to pass up to 5 or 6 cars. He has said many times that the only reason for this was because of his confidence in the tires.

Again, we don't sell Michelin tires so this isn't a sales pitch. Just our experience with them. I hope this is helpful.

 

[Vmax]

Oops, did not realize this thread was active! Ignore question.