2018 Season Prep NE

[Bad Horsie]

Thanks Norm, Hopefully I can test fit tomorrow. Will report back with some pics if I can

 

[Norm Peterson]

Here's a comparative plot. Strut side is to the left in all cases. It's close, but the black 275/40 line is clearly further away from the strut. The dotted lines in the upper left plot show this the best.




Norm

 

[stevbd]

OP, my apologies, my post wasn't clear. I meant to say you might consider spacers if you want a little extra spacing or if you just want to get the wheels as far outboard as possible for handling purposes. But I agree with the others here, I really don't think you NEED spacers to fit. My understanding is that you are using a pretty common set up. Also remember 18x10 with 43mm offset and 285 tires is a very common set up. So almost identical offset to yours but 1/2 inch wider rim works. I think you will be fine. Good luck.

 

[Pentalab]

I used the shank end of drill bits to measure the gap. (drill bits with round shanks, not the newer style 3 x sided types). With a 275-40-18 on a 18 x 10 rim, 45mm offset, AND a 3mm spacer installed, the gap was 21/64 (.328). Without the spacer, it's .21" . The spacer in this case is not required. Even with 285-40-18's on the same 18 x 10 rim, the gap is still .11" ... + no spacer.

Just try test fitting your proposed setup. I measured the gap, with wheels pointed straight ahead, then extreme CW..then extreme CCW. The driver's side gap was a tiny bit different vs the pass side.
If your wheel / tire hits the strut, don't crank down on the lug nuts ! Remove the wheel, and install a temp, single flat washer on each of the 5 x studs, then install wheel. Re-measure clearance. If a 2nd or 3rd washer is required to obtain minimum acceptable clearance, then just measure the thickness of the washers, and you have the required spacer thickness. 3mm spacer is a non issue, oem studs are fine. If a 5mm is required, then the longer studs are required. ARP makes longer studs in 2 x different lengths. The longer one is aprx 3.XXX". ARP long /short front studs are slightly longer than ARP long/short rear studs. If you have to use a longer stud, then the open style wheel lugs are also required.

 

[Bad Horsie]

Ok thanks guys, fit just fine.look great! stuck my finger in between the strut and tire up to my first knuckle then matched it to and open end wrench and got 11mm snug. took for test drive sunny out, OAT 45 degrees, couple clover leafs and curvy off ramps. they a little greasy but it is chilly and these are summer tires. they'll do.

thanks again

 

[frank s]

On my 2009 GT/CS I ran those GT500 wheels square with 285-40 tires for quite a while, including a few autocrosses, and a track day at Chuckwalla Valley Raceway, on "P" springs (about an inch lower than stock) with no rubbing anywhere.

My current setup is Shelby CS56 wheels—same specs as the GT500 wheels—with 275-40 PSS tires on a stock except for aftermarket sway bars 2014 GT convertible. I get a very small amount of rub only when backing up at full left lock. No rub on right full lock. I haven't been under to see where it rubs, but I'm guessing the Steeda adjustable front bar.

I think there is no strong reason to worry about 275-40s on GT500 wheels.

 

[Norm Peterson]

Ok thanks guys, fit just fine.look great! stuck my finger in between the strut and tire up to my first knuckle then matched it to and open end wrench and got 11mm snug. took for test drive sunny out, OAT 45 degrees, couple clover leafs and curvy off ramps. they a little greasy but it is chilly and these are summer tires. they'll do.

View attachment 66920

Those 275/40's must run a bit small - in that picture the tire section width looks smaller than the 255/45's I used to run on the same wheels. You've still got a wider tread, though.

Go mostly easy on them for at least a couple hundred miles. There's probably some mold release stuff to scuff off, and a few mildly to moderately driven heat cycles seems to help with longevity and resistance to chunking on the track.


It'd take a particularly unhappy combination of larger strut diameter and serious chasing of negative camber with camber/crash bolts to get any rubbing against the strut with that wheel & tire combination.


Norm