Higgie

OK,

As I get closer to thinking about some serious engine mod.s for my 05 GT, stick, I need to figure out if I can get enough tire, width, under Her to make it all worth while.

Any experience so far ??

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fin1

255 will fit all the way around. I've heard of ppl going with 285 all the way around w/o rubbing. Are you looking for more meat in the rear than in the front?

Higgie

Yes, I am considering the whipple SC to raise horse power to 450. I want to roadrace with friends at work. I figure I will need as much tire in the back as possible, for take off traction. Unless, I hera that the front and back need to be the same size for better handling, on a road course.

Birdieman4

Higgie, you might consider getting a set of tires and rims for road courses and racing only. It is the single best mod for road course performance. When you get into the soft racing rubber compounds, you won't need a very 'wide' tire. The racing rubber does wonders, even at a 255mm width. If you went with a slightly wider tire in back it would be ideal, but 255mm racing rubber would be a HUGE improvment for road racing.

F1Fan

Higgie,

The '05 Mustang as it comes stock is a pretty balanced car with the tires and amount of power it makes. The stock car's balance is moderate understeer that can be controlled with throttle in slow to medium speed turns. adding 30-40hp just gives you more options to adjust your car's line in a turn with the stock tires. Adding wider low profile tires with wider wheels takes those options away and balances the car to have more understeer than stock. To gain back the joy of throttle steering with wider tires you will need much more power than 30-40 horses, maybe 100-150hp more.

The problem is simply balance. If you had only a moderate amount of bolt-on power say 30-40hp more and used larger tires in back you'll just make the car push even more than it already does. For slow to medium speed turns like if you run canyons this is not a good setup. If you had an extra 100-150 horses you would need extra tire out back to handle the power and you could use power to get the car to rotate better. But more power can be a problem if it's not smoothly applied or non-linear in application, like large turbos tend to act. Blowers are going to act much better here but you will need to pay attention to your tunning to prevent having the power hit the tires too hard.

The best situation would be to have a set of tires and wheels for road courses (to maintain your car's handling balance for the power you are making), and a set for the strip. Obviously the strip setup needs to be very different than the road course setup but again wider is not always better. You need to pick a tire that will allow you to launch hard but not hook too much because you need some wheel spin off the line. Skinney's up front lower your E.T.'s when compared to wide sticky road race tires due to lower drag and weight, this is significant only if you are racing heads up or just want to go as fast as possible and not so important for brackets.

If you want your new pony to do well all around you must realize that you are talking compromise. Compromise is a good idea for a daily street driven car. If you want to be the fastest on the strip or in the canyons you will need to get different sets of tires and wheels and your suspension needs are also quite different and optimizing for one or the other will hurt you at the other end. To split the difference is called a compromise, good on both but not the best. I hope this helps you some.

Higgie

Thanks for all the info. I really didn't say enough in my opening post. If I do mod. the 05 GT, it will be blown for 450rwhp. Several members with real world blower experience, indicate that this level is doable, without doing the internals on the engine (whipple), is where I am leaning. Thus, I wanted to make sure the car can maintain a "package" that will be fun to drive, and preform well against others cars from work. There is a group that rents track time to play with their toys. Mostly Porsche, RX7's, Vettes, and BMW's here.

My decision is along the line of, 05GT Mustang + $10,000.00 to be competitve. With the realization that the mod.s money will maybe never be recovered at resale. Or, just do the 02-04 Vette Z06, or even a 05 C6 Vette. HP, tires, handling there for $32K-40K (I would do the basic 05 C6, with supplier pricing, around $40K.

I am at an age, and point in my life where this is a doable expense (OK, over 40, and I got divorced last year, so I want to go play).



Thanks again for your input. Additional comments welcome !!

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F1Fan

Hi Higgie,

My own cars have tended to be German though I restored a 1966 2+2 back in the day. I loved that car but it scared the bejeezes out of me with the way it handled and stoppped when compared to my highly modified 911 so I sold the '66 to my brother who just liked the way it looked and went in a straight line. I have been wanting to build another '66 2+2 ever since I sold the darned thing to him but it had to turn and stop in addition to go fast in a straight line. At the time there was no way to do this because this was back in the mid '70's. The only way to make it do this was to fabricate almost all of what it would need to perform at the levels I took for granted in my 911.

Speaking of vintage iron, another option that you might entertain is to buy a classic pony shell and restomod it. You know, put in a modern tubular K member and tubular arms with coil overs, drop a Torsen Diff into a narrowed 9" rear end and go with a 3 link + panhard bar rear end, tub the rear wells so you can get some meat under the car. Griggs Racing has this stuff off the shelf fully race engineered for less than you can fabricate it for. Add a rack and pinion steering kit for faster ratio and much improved feel. Tie the front and back halves together with some chassis tubes inside the passenger compartment using the roll cage and while it won't be as stiff as a say a new C6 it will work very well because the car weight will be so low and you will have more than adequate power. You'll have to add mild flairs to the fenders, add modern race brakes all around. Stir in a five or six speed gearbox and drop in an aluminium 331ci block with a Crane roller cam, an internally balanced and knife edged forged crank and rods with P&P'd AFI heads and a little bit of Barry Grant carb action and you would have a nice naturally aspirated 450-500HP say 2,800lb. (2,600 stripped interior), car you can drive on the street and clean up at the track with. With a $40K budget you could have someone do much of the work and use off the shelf parts to build it.

Sigh...

Higgie

Projects are cool, but as a single dad of a 12 year old son, who plays sports, I just don't get them done. I traded my 72 Plymouth Duster, that I owned for 15 years, big block 440 cu.in. 6 pk, carbs. 6 months ago for a 94 Harley, with the sheetr metal removed. It's still on the lift, haven't turned wrench one. I built the Dister, prior to being married/Dad. I cut it up, and caged it 6 years ago, pro-street, 18.5" wide rear tires. It sat with the drive train out for the last 6 years. -> converted it into Harley project.

I will finish the Harley, and thats my play money, around $10K tops. So, I really can't do a $40K project car, I will borrow most of the new car at our credit union. I'd rather play now at 4% interest, than save for 3 to 4 years to buy it outright.

Sure, I got issues......and I want to go fast !!

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Oh Yeah, there's no one at home telling me not to !! lol


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My son even said he would eat grilled cheese sandwiches for the next 5 years, if I got the Vette !! it was funny.

jeepmen

What's the widest tires that will fit on the stock GT rims (17x8)?
Or how do you calculate it?

Thanks,

Jeepmen

SpikeGT

Does anyone know if the stock tires on the GT will fit onto a 17x9 rim? the stock rim is 17x8. the stock tire size is P235/55ZR 17 Z tires. Any help is appreciated.