Red11

Have an 07 GT vert with OEM 17s. I picked-up some chrome 17X9 bullits (36mm backspace) that I want to put on for summers. I was told the tire that should go on these wheels is 255/50, can someone confirm that? As I understand it, this combo will stick out almost another inch from stock, finishing just inside the front fender lip. I'm kind of concerned this won't look good. Anyone else have this set-up. I prob will not stagger the back.

Are there any other size choices that will look and drive OK? There's not many tire choices 255/50.

Thanks!

adrenalin

Welcome to the forum. You could go with 255/45's on that rim. The 45 profile will keep the overall diameter of the tire close to that of the stock tire. With the 36mm backspace, just watch out for any rubbing that might occur when you turn the tires.

Red11

I see 255/45 will give me a lot more choices - thanx.

I'm pretty sure clearance will be ok, I've plugged the info into several online calculators and it looks good from what I can tell.

Ulf

Hmm are you sure about that. The factory rimms is 8 inches wide and 235x55x17 gives a diameter of 27,2 inch. 255x50x17 gives a diameter of 27 inches but 255x45x17 gives a 26 inches diameter and that would make a calibration of the speedo (and ev. auto) in the car computer to be nessesary. If you have an X-Cal or Diablo thats not a problem but the recomendation is to go with 255x50x17 If You don't want to do a recal. The wider rims 9 inch would actually make the diameter just a litle bit smaller than with stock rims. For checking tire size make a google for tire calculator or just try this http://www.miata.net/garage/tirecalc.html

A last point If You want the look with low sidewall 18 or 19 inch rims is maybe the way to go. Personaly I like a little moore "meat" on my wheels it's just that old school muscel car look.

Ulf

Red11

Doesn't 255/45 give me a tire almost 1 inch shorter than stock?

Red11

Exactly what I came up with. I don't have a tune (yet) but I know speedo would be 4% slower.

So I'm back at 255/50...with the same questions.

Ulf

You maybe should go with a litle wider tyre, maybe like 260x45x17. Try some different sizeses and se what You came up with. Here in Sweden the legal error for the speedomeeter is 5% so check what's leagal where You live. But it's not only the legal issues, the whole carcomputer would be "4% off" not only the spedo but shift points for auto and estimated miles left on the amount of fuel and so on. I'm not 100% sure that 4% is that much of an issue but these modern "computer cars" are sensitive little babies. And in my oppinion smaller wheels does not improwe the look, if anything I want a little bit larger weels to fill out the fenders or maybee an inch lowering like in the FRPP handeling kit. But thats just my 2 cents.

Ulf

Actually 285x45x17 is an almost perfect fit with a diameter of 27.1 inch. Then if there would be a good fit on a 9 inch rim is another question. Tire manufactuer usualy lists rim size recomdations on there home pages. There may ofcourse also be clearing issues and so on.

Red11

I'm gonna stick with 255/50 (or sell the wheels and get 17X8 or 8.5). This size is right on diameter-wise and .7 wider. Just wondered how it would look.

Ulf

When the weel "sticks" out more You usually got the illusion of wider tyres/wheels. Sometimes people adds spacers to stock rims just to get that look. If You like the wide tyre look in front and back and the rubber isn't rubbing against something I think You will be hapy with it. Just be aware that You in some small degrea are changing the cars handeling carakteristics and sometimes some insurance companys may use that as an excuse. There is also illegal to do in some places. I also strongly adwise against any kind of spacers on the front axle. If spacers are used on the rear be sure that You have enough treads in the weelnuts.

Hapy modding :-)

adrenalin

Makes me wonder. I have 255/45 on the front and 285/40 on the rear. Mine is 2005 GT. When I ordered my tires I went with 255/45/R18 since they gave me the most options when looking at tires. The speedo is not going to be off by much.

Red11

255/45/17 vs stock 235/55/17 changes car as follows:

When speedometer reads 60mph (96.6km/h) actual speed will be 57.6mph (92.7km/h): 4% slower.

Package is 10 mm (0.4'') closer to suspension/brakes components. Acceptable for most cars.

Package will stick out 10 mm (0.4'') farther. Acceptable for most cars.

I use a tire/wheel size calculator @ bigcustomwheels.com - very helpful.

Red11

my thoughts exactly - it should look "beefier" which should be good. i am also concerned with the setup throwing crap up the side of the car. my local shop offered to mount a 255/50 on one of my wheels, put the car up, and put it on the front and back to see if I like the look. i'll def take advantage of that offer.

Ulf

Yeah but did You say You have 18 inch rims or was that a typo? All numbers we have discussed so far are calculated with 17 inch rims. By the way I wonder if the speedo reeds the front weels or the rear weels or just the drivetrain. Probably the drivetrain I think.

Ulf

Ulf

Mudflapps maybe? You find them as FORD original options or at the aftermarket.

Ulf