Will 19×9.5 with +40 offset fit on the front of a 11 mustang gt? If so any tire size options would be appreciated

 

here is a link to the Ford Performance GT500 19x9.5 wheels with all the specs for a wheel that definitely works:
https://performanceparts.ford.com/part/M-1007-SA1995MB

Assuming the wheels you are talking about have the right bolt circle and center bore; the 40mm offset means that they will stick out of the fender 4mm more than the Ford wheels . . . that is about 0.2" so should not be a problem; depending on the width of the tires they probably will be flush with the fender or sticking out just a hair

for the tires, you want to:
1) match the overall diameter of the tires to your original tires within about 0.25" in either direction (otherwise the speedometer will be off, and if you go too big you could have rubbing)
2) match the width of the tires to the width of the wheels -- you can look up tires on Tire Rack to find the recommended wheel width

I have 19x9.5 44mm offset GT500 wheels on my 2010 and I run 275/40-19 tires; this gives an overall diameter a little bigger than the original and works for me.

 

Thanks for the info. As for the thread and bolt specs these rims are the Same as factory specs. I have non brembo front brakes. I truly appreciate the reply and I'm planning on using the 255×35×19 rims all the was around, so I dont think I'll throw off my speedometer in anyway

D.Morris

 

Hey D -- the "standard" OEM diameter for most tires on these cars is 27.2" ; not sure what yours came with, could be different.

here's an example of a 255/35-19 tire on Tire Rack (different brands may be slightly different, better to look up your exact tires, but this should be pretty close)
https://www.tirerack.com/tires/tires...omCompare1=yes

on the "specs" tab you can see:
diameter = 26" -- that is 1.2" "shorter" than the stock tires; or 5% smaller . . . so the speedometer will read 5% slower than you are actually going (assuming speedo was callibrated for 27.2" tires)
rim width range = 8.5-10" -- so your 9.5" rims are on the high end of the range which is "good"

also with the relatively narrow and short tires, there should be no rubbing issues but I can't guarantee that

 

255/40 19 was stock on the Performance Package and Brembo Package @ 27 inches, the stock 235/50 18 is 27.2 Like Bert said and the 245/45 19 is the size they run on the CSGT and it is 27.6 and I am running a 275/40 19 on mine and it is 27.7.
Those wheels are 7mm farther out than the Boss 302s wheels I am running or just a tad more than 1/4 inch