The Mustang Forum for Track & Racing Enthusiasts

Taking your Mustang to an open track/HPDE event for the first time? Do you race competitively? This forum is for you! Log in to remove most ads.

  • Welcome to the Ford Mustang forum built for owners of the Mustang GT350, BOSS 302, GT500, and all other S550, S197, SN95, Fox Body and older Mustangs set up for open track days, road racing, and/or autocross. Join our forum, interact with others, share your build, and help us strengthen this community!

Need help with tire fitment -- Boss and 350 Guys chime in

Hey guys, so I bought some Forester F14's for my Boss a year ago, and never had a chance to put tires on them. Now that race season is upon us, I will be buying tires for them this week, but Im having a hard time figuring out what will fit right. So here's where I'm at:

My front wheels are 19x10 +41 and rear are 19x11 +53

I want MPSS. I have been told that these tires run extra wide because they have a built in 10mm rim protector on both sides. So I'm thinking I may have to get 275/35/19 up front and 295/35/19 on the rear, because on MPSS it would make them 295 and 315 wide. Can anyone confirm this is correct/true? Those are disappointing widths for me to run, but if they really do run 20mm wide then I have no choice. I also don't want to go any lower profile than 35.

The other thing I've been looking at is the new MPSS that they make for the GT350. It is a 305/35/19, and it fits on a stock 11 inch wheel. I'm guessing that this tire is designed specifically to be put on an 11 inch wheel, which means I could run it instead of the standard 295/35/19? But I don't have any idea for sure. Does anyone know if those stock GT350 tires have the 20mm of rim protector?

Any advice is appreciated! I want to buy these tires as soon as I can decide what the hell will fit best. Thanks!

Mad Hatter

Gotta go Faster
Santiago, Chile
I have a set of MPSS for street 275/35-19 on the stock boss wheels (19x9 fronts) and they do fine, they are not much wider then my previous Dunlop 275/35-19 DZ2 street/track tires. My buddy has done really well with 19x10 with 295/30-19 and 19x11 with 315/30-19 tires (R7 in this case).

I would be very happy with PSS in 295/30-19 fronts and 305/30-19 rears. Only 0.3" higher in the rear .
I have those same wheels and offsets. I have the 295 30 19 MPSS in the front and the 305 30 19 MPSS in the rear. The rim protector from the rear tire does poke out a bit so it does not fit perfectly flush, although the rim and actual tire tread are flush. That tire combo seems to fit the wheel sizes well, and like already stated only have a .3" diameter difference. I did have to make a 1/16" spacer for the front to clear the brembo calipers by the standard minimum 3mm. I only ran this combo at the track a few times before going to a 18 x 11 square set-up. This combo with my AST coilovers and watts link provided a bit too much oversteer for me with the stock sway bars. I thought about trying the stock GT 24mm rear bar to make it more neutral.
Update: after doing some research and running some calculations with my local Discount Tire staff, I ordered 285/35/19 front and 305/35/19 rear MPSS. I'll let you guys know how/if it works.

TMO Supporting Vendors

Latest posts

Buy TMO Apparel

Buy TMO Apparel