THE Tire Thread

[Fubar]

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

The optional BBS forged wheels have the following specs:

Front Wheel:
5 Lug, 4.50" Bolt Circle
6.90" Back Spacing
50 mm Offset
18" x 9" Wide

Rear Wheel:
5 Lug, 4.50" Bolt Circle
7.295" Back Spacing
40 mm Offset
19" x 11.5" Wide

I'm just trying to make a thread that is easy to use for those looking to get something different. The questions are: What is out there? How does it compare to stock? Because the GT has a pretty big sidewall and tire manufactures basically list tire size by tread width, I made a comparison list that includes the new tire's expected sidewall height. I am not a tire expert (at all) so I am using formulas as I understand the tire measurement. I am more than happy to adjust my calculation if a more knowledgable person see errors with this methods. As it stands, my formula is:

Tread Width * Sidewall Percentage = Actual Sidewall Height
New Tire Height / OEM Tire Height = Percentage Change

Bridgestone Example:
345 x 0.35 = 120.75mm
126 / 120.75 = (0.9583-1) = -04.17%

OEM:Goodyear
F1 SuperCar
235/45-18 Front (105.75)
315/40-19 Rears (126.00)

Non-OEM: (Sidewall Height) Change from Stock Height

Michelin
Pilot Sport
Pilot Sport Cup
Pilot Sport PS2
Pilot Super Sport
245/40-18 Front ( 98.00) -07.33%
245/35-18 Front ( 85.75) -18.91%
-
345/30-19 Rears (103.50) -17.86%

Bridgestone
RE050A
265/35-18 Front ( 92.75) -12.30%
265/40-18 Front (106.00) +00.24%
255/40-18 Front (102.00) -03.55%
-
345/35-19 Rears (120.75) -04.17%

Hoosier
R6 - A6 - Radial Wet
245/35-18 Front ( 85.75) -18.91% - Wet Only
245/40-18 Front (110.25) +04.26% - All
255/40-18 Front (102.00) -03.55% - R6 Only
275/35-18 Front ( 96.25) -08.98% - All
-
315/40-19 Rears (126.00) +00.00% - R6 Only
325/30-19 Rears ( 97.50) -22.62% - Wet Only
345/30-19 Rears (103.00) -17.86% - R6 & A6

Pirelli
Pirelli PZero
* couldn't find a link for the corsa system
235/40-18 Front ( 94.00) -11.11%
-
345/35-19 Rears (120.75) -04.17%

Kumho
Ecsta XS
265/35-18 Front ( 92.75) -13.00%
-
345/30-19 Rears (103.00) -17.86%

Mickey Thompson
ET Street Radial II
245/40-18 Front ( 98.00) -07.33%
265/40-18 Front (106.00) +00.24%
-
305/35-19 Rears (106.75) -15.28%


* It goes without saying that one should always use caution when deviating from manufacturers original equipment.
* Also recheck manufacturer availability as they change their offerings quite often

 

[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/

 

[soroush]

Oem/oem

 

[Kingman]

Noticed that Sam's Club is selling the Michelin Pilot Sport Cup's.

 

[ViperJoe]

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:
Goodyear
F1 SuperCar
235/45-18 Front
315/40-19 Rear

Non-OEM:
Michelin
Polit Sport PS2
Sport Cup
245/40-18 Front
345/30-19 Rear

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?

 

[Fubar]

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?

Great question... I'm going to leave it for the original poster to answer. I am just trying to collect a quick list of currently used tire combinations.

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.

 

[SYCO GT]

Bridgestone RE050A
265/40R18

Bridgestone RE050A Scuderia
345/35R19

 

[SLF360]

Bridgestone RE050A
265/40R18

Bridgestone RE050A Scuderia
345/35R19

Is there rake issues with this ?

Do they fit into the fenders, or touch when retracting on bumps...?

 

[GERMANORACING]

Is there rake issues with this ?

Do they fit into the fenders, or touch when retracting on bumps...?

I personally feel that the 255/40R/18 are a better fit then the 265/40R/18

 

[Kingman]

Bridgestone RE050A Pole Position
265/35R18

Bridgestone RE050A Scuderia
345/35ZR19

 

[Yukonranger]

Are either the RE50A or the RE50A Pole Position front tires an exact match for the RE050A Scuderia rears?

 

[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.

 

[Fubar]

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.

I was just talking about a different size wheel.

 

[Specracer]

I am currently driving Hoosier R6's on the street.

 

[Fubar]

I am currently driving Hoosier R6's on the street.

Stock tire sizes?

 

[Specracer]

245 front stock in rear (315)

Stock tire sizes?

 

[SYCO GT]

Extensive thread info available at this link for the RE050A...

Is there rake issues with this ?

Do they fit into the fenders, or touch when retracting on bumps...?

http://www.fordgtforum.com/forums/showthread.php?t=10821&highlight=heritage+bruce

 

[HeritageBruce]

Bridgestone RE050A
265/40R18

Bridgestone RE050A Scuderia
345/35R19

Syco GT, HHGT and I all have the same size brand tires and I think all three of us are very happy.
I just ran an autox two weekends ago and the setup was quite neutral, the tires got a little greasy after 7 non-stop laps though but not bad for a street tire. I have a video clip posted somewhere else on this forum of one of the runs where the tires got a greasy and I spun out but it was partly my fault as I was pushing too hard into a off chamber turn.

 

[Kingman]

Are either the RE50A or the RE50A Pole Position front tires an exact match for the RE050A Scuderia rears?

The Pole Position and Scuderia's tread/sidewall sure look the same.