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Discussion Starter #1
I'm going to be running my Cobra at Willow Springs on Oct 3-4 so I'm going to be buying some new track tires. The rims I'll be using are Steeda Ultra Lights that are 17x9.5 front and 17x10.5 rear so I'm going to run a larger tire in the rear. I've decided to go with either a Nitto NT01 which I had before (245/45/17 all around) or the NT05. I loved the NT01. Due to cost, if I go with the NT01 I'll run a 255/40/17 front and 275/40/17 rear. If I go with the NT05 I'll run a 275/40/17 front and a 315/35/17 rear.

My question is will the wider NT05 be as quick as the narrower NT01? If not I'll go with the NT01. If the NT05 will be just as quick then I'll go with it since they are still cheaper than the NT01 even though they are wider and they'll last longer.
 

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I dont know much about the comparison of grip levels compared to the softer compounds (05 compared to 01)

however like im sure many will come in here and say, run a square setup 275s all around
 

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1" wheel width difference won't matter much. I run 255x4 on 8.5/9.5 wheels. No big deal. Size the tire for the smaller wheel and the wider wheel will appreciate the little extra stretch.
 

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Discussion Starter #5
Is the even size so that you can rotate them from front to rear for wear? I have 98 Cobra rims (17x8.5) for the street and run 255/40/17 all around so I can rotate them.
 

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It's because mustangs are front heavy. If you run a smaller tire up front, you are overworking the front tires and underworking the rears which will usually create understeer, which Mustangs already do enough of. Do some of us still do it? Yes. For instance, I ran 305 rears and 285 fronts on my 18*10s last year and much of this year. I got the two difference sizes because I knew the 285s would clear the front without hackage and I wanted the 305s so I could test to see if they would clear as well and then run them on the rear (they didn't). I now run 25x12 bias ply rears and 23.5x11.5 fronts on 12" wide rims. Next year, I plan to run a square 25.5x12.5 radial setup as I've clearanced the front for the larger size tire.
 

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If you run the same width tire on a 1" wider rim in the rear, the back of the car will be much more predictable than with a wider tire on that same wheel. This is really important when turning into +100mph corners. You need confidence to know what the rear is going to do.

To get good performance from a given radial tire, the tire width and rim width should be the same. For a 275 tire that is a 10.8" wheel. The vast majority of people run tires that are far too wide for the wheels they are on. If you look at any race class where the tire width is rules limited, but not the wheel width, the wheels are wider than the tire.

After you have run a couple of track days on the wheels and tires rotate the tires between the wheels to even out the wear.
 

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It seems I wind up saying this a lot...LISTEN TO JACK!!!

A good, compromised starting point for a street/track car is to run an equal width rim/tire combo...which puts you at about a 245mm-255mm up front & a 275mm out back with you current rim selection.

For a car that see's more track time or if you want optimal performance & are willing to give up some daily driver comfort, you should run a tire that has a "tread width" that is 1" narrower than the width of the wheel...which would be 235mm up front & a 265mm out back with your current set up.

We ran that exact wheel/tire size combo on my cousin's '97 at Streets of Willow with great success! The car was well balanced & predictable...especially for a street car with very limited suspension modifications.
 

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My question is will the wider NT05 be as quick as the narrower NT01? If not I'll go with the NT01. If the NT05 will be just as quick then I'll go with it since they are still cheaper than the NT01 even though they are wider and they'll last longer.

The narrower NT01 will be faster than a wider NT05.

Frank
 

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Discussion Starter #10
So I'm a little confused now. I'll be using 9.5 front rims and 10.5 rear. So should I go with 255/40/17 front and 275/40/17 rear or should I go with 275/40/17 on both?
 

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And no, the NT05 won't be as fast as an NT01 no matter what you do.
 
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