[Benboi92GT]

Hey guys, I'm new to the forums and I signed up because after extensive google'ing I still haven't managed to find the answers to my questions!

My first question is about tire size. I know there are threads upon threads of this and I've looked at them all but still haven't managed to find an answer! I need to know what is the biggest STREET tire I can put on a 15x8 prostar and still have it fit under the 92 GT with no modifications. I'd rather not roll any fenders and sure as hell don't know how to remove the quad shocks =P I've found plenty of info on sizes for slicks and DR's but I literally drive this car every day so I need street tires =) Also: I've been to two tire places so far and have received incredibely different answers. One guy told me 145/60/15 is the largest, and another guy told me 225/50/15, wtf? What gives, lol

Second, every once in awhile while driving or in idle, my CEL will randomly (and I mean randomly) come on and if in idle it will start surging, while if Im accelerating or giving gas it will do a sort of buck/cut out until the CEL goes back off. I'm thinking bad IAC? Possible?

Thanks for the help guys, glad I finally signed up on here =P

[ryanw]

i believe the quad shockes are just 2 bolts, and they can be removed or swaped over to the other side which will give you more space to run a wider tire. im also unsure of how wide a tire you can used. ive heard of people running a 275 tire but i think they had to bash in the inner part of the fender and roll the outer lip of the fender. i think you can get away with a 255 and do no modifacations...when i first got my car i had 245 on the rear with no issues and that was with quad shocks

[Benboi92GT]

Thanks ryanw, how did the 245s look? Pretty wide and fill up the wheel well alright? Basically I want it to look as close to the fat DR/slick look but still have the driveability, it is a dd after all =P

[mab]

i have 255s on my 85 gt and it fits fine plenty of room for more. i tried on some junk 12.5 inch mickey thompsons and they were rubbing on the quad shocks so if i can take those off then they'll fit! i didn't know you can run it with out them?

[ryanw]

Originally Posted by Benboi92GT Thanks ryanw, how did the 245s look? Pretty wide and fill up the wheel well alright? Basically I want it to look as close to the fat DR/slick look but still have the driveability, it is a dd after all =P

they looked awesome, but like i said you may be able to get even wider on there. i have 235 right now just because of cost reasons but when the time come and i go to a 15x8 wheel ill get the biggest tire that will fit, but my car will only be driven a few times a month so cost wont be a factor any more

[ryanw]

Originally Posted by mab i have 255s on my 85 gt and it fits fine plenty of room for more. i tried on some junk 12.5 inch mickey thompsons and they were rubbing on the quad shocks so if i can take those off then they'll fit! i didn't know you can run it with out them?

if your not going to use your quad shocks then you need some good after market upper and lower rear controlling arms, but ive heard that you can take the quad shocks and bolt them on the other side of the mounting bracket (which was what i was saying about putting them on the other side)which will allow you to keep the quad shocks and give you more room for a wider tire.

[Benboi92GT]

Cool, so 255/60/15s then is probably what I'll aim for. Do they make tires in that size? =P

[ryanw]

Yes

[5.0freak]

you can remove quad shocks for more clearance, they dont serve any real purpose on the suspension. If you have a 5.5 backspace on your wheel, and if it was purchased for a mustang it most likely is, you can fit a 275/50/15 with no problem. if you dont want to remove the quads you can try moving them to the other side but you will probably run into issues. Most likely you will have to run a 265 in that case. With stock ponies you can run up to 255/50/16 with quads, no modifications.

[Benboi92GT]

Okay, thanks again for all the responses! If it is something like a 4.5 backspace would a 255/60 still fit? Still a bit in the dark on how that affects everything

[ryanw]

not sure either but the back spacing should be 5.5" in...just go with that you know works.

some people may run a 5" back spacing with a 1/2" spacer...but if you havent gotton the wheels yet, then just get the 5.5

[Benboi92GT]

Got the wheels in a trade for an old rifle I wasn't using, just measured and they are 4lug with a 4.5" backspacing, rut roo Wonder what that changes

[VM0824]

Originally Posted by Benboi92GT Second, every once in awhile while driving or in idle, my CEL will randomly (and I mean randomly) come on and if in idle it will start surging, while if Im accelerating or giving gas it will do a sort of buck/cut out until the CEL goes back off. I'm thinking bad IAC? Possible?

run a CEL self test. you just need a jumper wire, pad, and pen. that'll help zero in on the problem.

[VM0824]

not to threadjack but i really really need some traction. i have some 15x7's and some 17x7's and want to find the biggest tires that fit. biggest ive found are 245/45/17's. can i fit like 17x9's in the back?

[5.0freak]

Originally Posted by VM0824 not to threadjack but i really really need some traction. i have some 15x7's and some 17x7's and want to find the biggest tires that fit. biggest ive found are 245/45/17's. can i fit like 17x9's in the back?

You can fit up to 17x10's on the back but you have to have correct backspacing and no quad shocks, possibly minor modification to fender wells. the best i can recommend is to find out what backspacing you already have and call that wheel manufacturer and ask for recomendations. another option is to find your current wheel backspacing and measure all your clearances and call a wheel manufacturer or tire manufacturer and provide that info and the ask for tire sizes.

here is a sheet i use sometimes, this should give you a good start if you decide to go this route...

Billet Specialties - Measuring Guide & Order Form

[VM0824]

what happens if i delete the quad shocks though. then i need new rear suspension?

[ryanw]

if your going to delete the quad shocs should get some better upper and lower rear controlling arms. but if you look at how there mounted, swap them on to the other side of the bracket, meaning bolt them in from the other side, but you really dont need to do this unless your running bigger tires