Possible Tire Change !!

[2002_Viper_GTS_ACR]

Hey Guys,

So as I watched more snow fall in Chicago the other day, I thought how painful this process is of waiting for good weather until I buy my GT. But, it gave me some time to think about both of the weaknesses I keep hearing about the GT, the braking and the handling, relative to the Vipers and Z06s.

Keep in mind, I mention that because I love the Ford GT, and want it on top in all catagories. So I really believe the number one culprit of this is the damn tire selection that Ford came up with. I think thats such a critical componet to both stopping distance and handling, that in fact both may be improved by simply selecting better tires. So here is my shot:

Stock:
Fronts: 235/45/18 Tire Size 9x18 Rim Size RRadius: 26.3 inch
Rears: 315/40/19 Tire Size 11.5x19 Rim Size RRadius: 28.9 inch

Proposed: (change to Michellin Pilot Sports)
Fronts: 285/35/18 Tire Size 9x18 Rim Size RRadius: 25.9 inch
Rears: 345/30/19 Tire Size 11.5x19 Rim Size RRadius: 27.4 inch

Rolling radius is important for keeping speedo and ABS functioning properly.

Keep in mind, I have had a LARGE success rate when coming up with such combinations on all of my Porsches and my many Viper tire selections.

The only concerns I have on my selections:
1. Ideally a 285 front likes a 9.5-11 inch rim, I'm fairly sure its ok here.
2. Ideally a 345 rear likes a 12-13.5 inch rim, again fairly sure its ok here.
3. Does the clearance exist in the wheel wells for these larger tires without rubbing shocks, A Arms, outter fenders, inner plastic wheel wells. (I dont own a GT yet, so I cant check any of this, if I had one, I would know the answers easily).

Ok, thats my rant, I really think this would be the PERFECT street combo for this car, maxing out tire patch, and grib, for acceleration, handling, and braking !!

Unforutnetly, right now there are no Michellin Pilot sport CUP tires available in 19's that work for this set up, because those are a decent set of Road Racing (track) tires.

Jon

 

[Jason Watt]

Jon,

Nice post...



I'm pretty sure a 285 will NOT work on a 9" rim. There will be way too much "balloon" and the rim will move too much side to side in the tire when cornering.

As for the rear I think a 345 could work. The smaller radius is great because the gearing is quite tall.



There was a rumour that Hoosier was to release some DOT approved street slicks in the sizes to fit a GT - that would be the way to ..

 

[2002_Viper_GTS_ACR]

Jon,

Nice post...



I'm pretty sure a 285 will NOT work on a 9" rim. There will be way too much "balloon" and the rim will move too much side to side in the tire when cornering.

As for the rear I think a 345 could work. The smaller radius is great because the gearing is quite tall.



There was a rumour that Hoosier was to release some DOT approved street slicks in the sizes to fit a GT - that would be the way to ..

Thanks 1 of 101 .

But I still stick by my assessment, I believe its correct. The tires that are on the Ford GT right now up front are the SMALLEST allowable size, per tire rack for a 9.5 inch rim. Where as my suggestion is a hair bit more the the LARGEST allowable size.

This same deal of pushing the envelope slightly has always worked on my porsche and viper selections. I typed this whole detailed explanation and gave measurements, only to have the web browser lock up when I was submitting it, so I dont feel like explaining it again. But I am very certain in this being ideal, as long as the tires will fit with no rub in the wheel wells, going lock to lock up front.

Jon

 

[AMB]

Possible Tire Change

A problem, I see, is the back WILL be lower, by about .5" than the front !!

AMB

 

[2002_Viper_GTS_ACR]

A problem, I see, is the back WILL be lower, by about .5" than the front !!

AMB

Correct (kind of) my good friend, here are the rolling diamiters for my recommendations:
Front= 25.9 inches
Rear=27.4 inchest

BUT, can you believe the CAR as it stands now is WORSE then that?:
Front = 26.3
Rear = 28.9

So if you are bothered by my 1/2 an inch, this Full inch has got to be killing you :biggrin But in actuallity my set up lowers the car all the way around just a hair, but your wrong about the rear being lower then the front. Even if I just lowered the rear tire size and never did the front, the rears are STILL larger diameter then the fronts, so reducing their size, still doesnt get it lower then the front.

Jon

 

[AMB]

Possible Tire Change

You need to COMPARE the OLD front tire to the NEW fount tire DIAMITER and the OLD rear tire to the NEW rear tire DIAMITER. The NEW conation will have the REAR of the GT, about .5" LOWER than the FRONT !!

AMB

 

[2002_Viper_GTS_ACR]

You need to COMPARE the OLD front tire to the NEW fount tire DIAMITER and the OLD rear tire to the NEW rear tire DIAMITER. The NEW conation will have the REAR of the GT, about .5" LOWER than the FRONT !!

AMB

I get that you want me to compare the old to the new. But it is not going to be lower then the front. You would be more correct in saying "the new set up lowers the rear by 1/2 an inch more then the OLD set up" because this other stuff about the car being lower then the front, is just not true.

And these cars sit too high to start with, so one of the things I would investigate is doing a corner balance on it, and lowering the over all height of the car in order to lower its center of gravity also. Sorry, im very track/street performance minded, its why I bought the ACR version of the Viper, and if they had such an option for the Ford GT, I would buy it too.

Thing is, tire combo sucks for the Ford GT, it has more power then all of the other cars, and has the smallest tires. How much sense does that make. :frown

Jon

 

[dbtgt]

The tires on this beast are clearly not Goodyears - maybe there is some R&D info to be had from these folks.
http://www.svtperformance.com/forums/showthread.php?t=231456