MK III newbie tire question

wedgerton · #1 (**permalink**) 05-05-2010, 06:17 AM

Hello all,

I'm a newbie to the Cobra arena and had a question on tires. I recently purchased a MK III that was barely started. It was basically almost like starting from scratch. Anyway this person had already purchased tires for the car which are 275/40 ZR17 for the rear and 245/45 ZR17 for the front. I'm debating about buying a set of 315's for the rear and 275 for the front. I've read where some of you have had trouble with theses tires hitting the sheet metal etc.

With my brief description do you think it's worth it to change out the tires I have? I don't plan on doing racing with the car but mostly cruising a little and possible show get togethers. I may hit the track a couple of times but not as a normal practice.

Wayne Edgerton
Flower Mound, TX

Fraser · #2 (**permalink**) 05-05-2010, 11:23 AM

Wayne,

Firstly welcome to our group. The tire sizes you have are exactly the same setup as I am using on my build (245/45 R17 front, 275/40 R17 rear) and although like you I am still in build this was my thoughts and what I have also found.

Even with 245/45 R17 front I needed to use rack limiters as the inner tire wall rubbed on the F panel at the extent of travel.

With a 26" diameter limit the largest obvious choice is 315/35 R17 on the rear and possible 275/40 R17 front or any combination in between. So my thoughts were to start with the smaller (have already found rubbing) and once complete decide if I want to go bigger on the 2nd set of tires. I guess I won’t be able to resist a few burnouts and doughnuts early on, plus it may take some tweaking to get alignment perfect which could induce excessive wear so don’t envisage keeping the first set of tires to long.

Rear axle can make a difference, 79-93 Fox Mustang width: 59.25” hub to hub, anything newer is wider and subject to rubbing.

Short answer, you should be just fine with what you have.

bobcowan · #3 (**permalink**) 05-05-2010, 12:11 PM

Fitting 315 tires on a FFR MII requires surgery to the frame. Not worth the effort, IMO.

Stoney FFR · #4 (**permalink**) 05-05-2010, 07:09 PM

Quote:

Originally Posted by bobcowan

Fitting 315 tires on a FFR MII requires surgery to the frame. Not worth the effort, IMO.

Bob, grab your glasses! I think he said he has a MK I I I ..

I was more curious as to whether or not he had a Factory Five or some other brand of MK3.

With that said, I have 315's and they fit fine on my FFR MK3 Roadster.. Tires are only part of the equation though. I'm sure you need a wheel with the correct offset and backspacing too.

bobcowan · #5 (**permalink**) 05-05-2010, 07:36 PM

Dang it, I hate getting old!

One of the mods for the MIII is to widen the wheel well to fit the 315's.

But, that is mostly a cosmetic change. People who race don't like the 315's. They're so wide on such a light weight car that it's tough to get some heat in to them, and they don't stick. But they sure look great. And, on the street, I don't think it will matter.

wedgerton · #6 (**permalink**) 05-06-2010, 05:04 AM

Joe,

As I said I'm a newbie. I'm building a FFR. I didn't know the other brands also had an MKIII.

Wayne

Tim Brewer · #7 (**permalink**) 05-06-2010, 08:09 AM

Hey Wayne, I have 315's on my Lonestar. I also live in Flower Mound if you want to check it out, I would like to check out your progress on your car as well.
Tim

JCoop · #8 (**permalink**) 05-06-2010, 11:48 AM

Quote:

Originally Posted by wedgerton

Hello all,

I'm a newbie to the Cobra arena and had a question on tires. I recently purchased a MK III that was barely started. It was basically almost like starting from scratch. Anyway this person had already purchased tires for the car which are 275/40 ZR17 for the rear and 245/45 ZR17 for the front. I'm debating about buying a set of 315's for the rear and 275 for the front. I've read where some of you have had trouble with theses tires hitting the sheet metal etc.

With my brief description do you think it's worth it to change out the tires I have? I don't plan on doing racing with the car but mostly cruising a little and possible show get togethers. I may hit the track a couple of times but not as a normal practice.

Wayne Edgerton
Flower Mound, TX

If you're referring to a Superformance Mk III, then you should go to a 315/35 ZR17 rear like the Nitto NT01 shown here. I have them and they grip like glue. softer compound than the NT05 which last a little longer. Match with 255/40 ZR17 fronts. The 275s may rub on the frame at the extreme ends of your turning radius. Let me double check the front size I installed.

Sorry for the big pic...oops, didn't catch your last post re: FFR. Should still be good tires for it. Discount tire direct sells them.

Don Gentry · #9 (**permalink**) 05-12-2010, 10:28 AM

I'm using 275's and 315's on my FFR MKIII, but like Joe mentioned it also depends on your wheel/offset. Of course I also used the IRS not the stock Mustang rear. I did have some rubbing so I bought 1" spacers and moved the rears out a little. I really like the way the fill the space in the rear, but I will probably go with 245's in the front when the time comes because they do rub a little.

I live right over in Carrollton so if you'd like to swing by some time and take a look at my setup drop me a pm.

wnkalvarez · #10 (**permalink**) 05-15-2010, 12:21 PM

I live in Flower Mound as well and just put 275/40/17 and 315/35/17 on my SPF, your welcome to stop by and take a look.

Madmiles442 · #11 (**permalink**) 05-15-2010, 09:07 PM

I had 335 and 275's on my SPF and the front rubbed a little on the inside frame on a lock-to-lock turn. I loved the way the 335's filled out the wheel wells. I've sinced changed to Blue Streaks which are close to the same width but come with other "attributes."
Check out the Tire and Wheel forum, you might find some more feedback there too.
Welcome to your addiction!