MustangForums Editor

Check it out here: Inside Line's GT500 vs ZL1 Track Test

Dyno runs are one thing. Track performance is a whole 'nother beast. This video isn't a very "exciting" one, but it does cover all the basics nicely. Grip, quarter mile time, braking. It's kinda like a video spec sheet.

angryBits

I wonder how the Shelby would do with the same 285 & 305 tires as the ZL1.

angryBits

Maybe http://www.shelbystore.com/Shelby-Wa...s5m-5649-m.htm ?

MrBlack2012GT

They say the ZL1 will pull slightly more g-force....but did anybody notice the horrific UNDERSTEER with that ZL1? Kinda defeats the purpose of those fat tires if you can't get your car to turn in at higher speeds. SVT went with 265 fronts and 285 rears because if they went any larger on the front tires, it would negatively affect turn-in response. They didn't go too large on the rear tires because if you go too large out back and leave the front tires the same, it causes understeer, and to avoid the understeer they'd have to go larger on the front tires as well, which, again, negatively affects turn-in response....it's very much an "all-around" car, the new GT500. Road course beast, drag strip beast, and top-end beast. It doesn't understeer if you go into a corner too fast, the back end starts to come out instead, which helps rotate the car, unless you don't catch it in time....lol

angryBits

I saw the video where they were talking to Jamal Hameedi about that but apparently the mustang could use more grip in the corners as well as straight line. My GT500 is on order and should be here in a week. I'm just going to drive it as is until the tires fall off then think my options.

MrBlack2012GT

Yeah it could use more grip, I think their best option as of right now is going with an improved tire compound next year, along with some suspension tweaks. I still say the ZL1 having more grip won't mean anything if the understeer is as bad as shown in the OP's vid. That in itself will slow it down alot.

candymanjl

It's all about the relationship front to year. There's no magic tire size since every tire compound is different. A 265 from one company may grip like a 285 from another, or a 245 from another. Plus if you look on Tire Rack and search by size each manufacturer ends up with different widths even when you pick the same size. My old car ran 245 rears stock and I found up to a 1" difference in tread width between different manufacturers even though they were all "245" tires.

For all you know they went with those sizes because anything larger would have dropped their MPG too much and put them into a gas guzzler tax. I know I lost a few MPG when I changed to my wide tires. Or bigger sizes would have ate into their profit too much. Just because that's how the cars comes from the factory doesn't mean that's the holy grail of engineering. Manufacturers have to make tons of compromises to get a car onto the street.

I'm running 275 fronts and 305 rears right now and I've got tons of grip. Holds a line and I can still oversteer if I want to. I used to have an S2000 and I remember guys running 285's all around with lots of success. National SCCA champion guys, not just weekend warriors guessing at setups. Nobody stuck to the stock 225 fronts and 245 rears just because that's what the factory did, they would be in the back if they did And I'd bet money that if Ford had a factory road race car it wouldn't be running 265's and 285's, more like 345's, ha ha.