oceantracks

OK first off I really don't understand much about tire sizes, suspensions, etc.

We have 2014 GT and the Pirelli's it came with are shot already at 18,000

From a looks standpoint, I think slightly bigger tires would be cool, especially on the back.

So....what do you guys suggest?

Keep the factory size on the front, then bigger (if so, what size) on the rear?

I was told that changing sizes at all would mean a new tune....does that affect warranty?

Thanks much
Tom

dmichaels

Many many people run wider rear tires on the mustangs. You can get wider tires that very closely match OEM tire outer diameter so your speedo will remain accurate.

On stock rims you can usually go up to two sizes wider, such as going from a 255 tire to a 275. Lots of options

Post your current tire size and we can help guide

oceantracks

Hey thanks I just checked and I have 235/50 ZR 18 97 followed by what looks like a "w"

I'm trying to keep my wheels to save money for now....and I'm just wondering how big I can safely go without adversely affecting performance like cornering, etc.

Thanks!

dmichaels

Typically wider tires are more performance oriented. A wider rear tire will result in more traction from the rear tires (in general, assuming matching tires front and rear in terms of tire make/model). By increasing rear grip, the handling of the car will be more towards understeer at the limit, which in general is "safer" in that the front just pushes away rather than the rear coming around.

I have run square (all tire widths the same) setup on the street and at the track as well as staggared (wider rear tires), and personally I like a square setup best, but I also have years of experience driving in a track environment and understand the cars handling dynamics quite well.

If I were you, I'd consider looking at a 255/45/18 tire for front and rear. That would result in about 0.8% lower speedo reading (70 mph indicated would be 69.4 mph actual. Negligable difference), and the slightly shorter sidewall would help handling a bit.

You would have to double check your wheel widths to ensure you could fit a 255 tire on there (the wheel will have 18x7.5 or 18x8 or something marked on one of the spokes). Then you can simply go on Tirerack and check out tire specs. The min and max recommended wheel widths for every tire on there is listed.

kcoTiger

This is just my opinion, but if you're going to go for big rear tires you will need to get a set of wheels that will accommodate them. Going from a 235/50/18 to a 255/40/18 will give you roughly the same diameter (I'm guessing, the numbers won't be exact, and a 255/45 might be closer) with a wider tire. But a 255 isn't going to help you all that much in terms of performance. If you want wider tires, go WIDE. As in, 305s or 315's. They will provide a significant difference in traction and will require a 10.5" or 11" wheel to fit properly. Save your money and get something that fits roughly what you have now, then when you have the cash to lay out for a set of wider wheels AND the tires to put on them, you can think about getting really wide. Again, all of this is just my opinion.

dmichaels

Can't argue the above, nothing wrong with that approach, depends on personal preference

As a counter point, I track my car at various road courses with a 275 width tire and keep up with just about everything out there. Would I gain much from a 305? Maybe a bit, but I like the significantly lower prices of slightly narrower tires and I get grip all day long depending on tire compound selection.

Lots of options to suit lots of budgets and personal preferences!

dmichaels

Did you mean 2004 or 2014? Huge difference in the cars....

laserred38

Most likely 2014. 2004s didn't come with Pirellis stock...

kcoTiger

If I used 275's, I'd be buying new tires every six weeks because I'd leave strips of them at every stop light. Hell, I had my 888's get loose on me last night at a little past half throttle, though it was my own fault because they were cold and I knew better.

oceantracks

OOPS...I mean 2014!

dmichaels

Yeah, you definitely drive the car a bit differently than I do! I use 1st gear about once a month I think, always start out in 2nd and am rarely into the throttle until 3rd gear.

888's need some good heat in them to have grip. Even my OEM tires will absolutely light up rolling on the gas in 3rd when it's below 50 out and tires are cold.

With my BFG R1's, I basically can't get the rear to step out if I try once they are hot.

Anyways, to the OP, look at tire compound seriously as well aside from just width.

oceantracks

So would these work?

http://www.tirerack.com/tires/tires....num=35YR8PSSXL

The factory specs on my car say "P235/50R18 all-season; 18 x 8.0-in. wide-spoke painted aluminum wheels;"

Thanks!
Tom

dmichaels

Yep, those Michelins are excellent tires, and that pricing looks quite good. You'd likely notice a huge difference just going to that tire compared with the OEM all seasons.

laserred38

Those 275s are too big for your stock wheels. For an 8" wide wheel, you really shouldn't go wider than a 255. But that is a good tire. Do you drive in the rain/cold at all? If so, get the A/S 3s over the Pilot Sports.

kcoTiger

Well I think it has as much to do with the fact that I have more than enough TQ and HP to shred anything but a steamroller barrel, but yeah, I probably do use it differently than you do yours. My gears are 3.08's so I stay in 1st through about 30mph before going up to 2nd. Even with those gears, it's still impossible to keep it from spinning when the tires are cold without grandmothering the throttle. But that's ok, since when their hot, they do a very good job of holding the car on the road and providing traction, and it's hot here a lot more than it's cold.

dmichaels

The link brought me to a 235 tire, but i might have caused confusion with discussion of my setup.

The 235 Michelins would be excellent for summer tires. Excellent point about cold or snowy conditions though

dmichaels

Yeah, just noticed GT500 for you... yep, slightly different power than my car!!!

oceantracks

Yeah and I actually meant to find a 255 tire, but couldn't find one that was
255/45/18....think I found "19"....but I suppose that won't work.

So at that price for the 235 (and it's a great tire I know), I might do that and just wait until I had $ for bigger wheels, or else double check tomorrow at the tire store near me whether Michelin Super Sports come in 255/45/18.....

oceantracks

BTW, I'm in FL, so no snow and ice to deal with, although in Summer it rains a lot...

laserred38

The Super Sports aren't going to be that great in the rain. To be honest, I'd just look at replacing the stock tires for as cheap as possible, and save up for a summer set of staggered 20s with summer tires.