Rear tire fitment and rear wheel offset/backspace question

[Steve87GN]

Hey guys, long time no post. So, I'm looking at buying more goodies for my little Buick again and want to get some new wheels. I'm looking at the American Racing Salt Flat Specials, painted black instead of grey with the polished lip/lugs/center cap, 17x8 in front and 17x9.5 in the rear. Here's a pic for a quick referrence...

So, to my questions. I'm looking at running either a 275/40/17 or a 285/40/17 in the rear, but am not sure which will fit without having to modify the car (assuming proper wheel offset/backspacing). I'll be replacing the current springs, front and rear, with a set from Kriban (already have them, just not installed yet). The current shocks are Gabriels and still feel pretty firm, but I am looking at going to Bilsteins in the near future. Can I run a 285/40/17 without any problem? If so, then what would be the correct offset/backspacing (American Racing sells those wheels with a custom backspacing from 3.75" to 7.25")? Thanks in advance everyone.

 

[rk87gnnj]

Torq Thrust II's - same question different wheel

I'm pondering the same dilemma exactly as you except w/TT 2's instead. I've actually just purchased (2) 17x8's w/4" bs for the front. I intend to install 245's in either a 40 or 45. Being that I will be dropping the car 2" F & R (springs) I was hoping that the smaller diameter of the 40's would ensure they would not rub the fender. Any feed back by anyone would be appreciated. Would I be getting greedy to think I can fit a 255 in there?

For the rear American Racing offers the 17x9.5 TT2's with custom backspacing as well as the ones you have chosen. From the info I have scoured on the boards, the 275/40's should fit fine with 4.75" backspacing. My question as well is whether or not I can get the 285's in there as well - especially since the car will be dropped 2". Because I have fender flares I want to fill out the fenders, but prefer not to have to cut, roll, or notch. It seems that every project leads to breaking out the torch, grinder and welder :smile:

If anyone can help out with these questions, and also have photos, please let me know.

F (2" drop) 17x8 4" bs with 245/40/17 or 245/45/17
R (2" drop) 17x9.5 4.75" bs with 285/35/17's

Will these scenarios work with or without additional mods?

I am new to the boards and want to say that I have gained a ton of knowledge from them. Thanks

 

[toofastforyou]

I'm no expert, but I know by experience that any rear spacing more than 4.5 will probably give you some frame rubbing issues no matter if the wheels are 15", 16" or 17" dia. or more... As for fender clearance, it depends on the overall diameter, and even more important is the height of the wheel/tire combo as the place where the tire is more likely to touch the fender lip is at the top of the wheel opening.
Hope this helps...

Claude:smile:

 

[rk87gnnj]

Backspacing issue

Thanks for the feedback. Perhaps I was being overly optomistic knowing already that 4.5 is the max. bs rule of thumb. I'll take the advice of those with personal experience over the measuring tape any day of the week. I guess thats why we are all here. :smile:

 

[jdpolzin]

I'm pondering the same dilemma exactly as you except w/TT 2's instead. I've actually just purchased (2) 17x8's w/4" bs for the front. I intend to install 245's in either a 40 or 45. Being that I will be dropping the car 2" F & R (springs) I was hoping that the smaller diameter of the 40's would ensure they would not rub the fender. Any feed back by anyone would be appreciated. Would I be getting greedy to think I can fit a 255 in there?

For the rear American Racing offers the 17x9.5 TT2's with custom backspacing as well as the ones you have chosen. From the info I have scoured on the boards, the 275/40's should fit fine with 4.75" backspacing. My question as well is whether or not I can get the 285's in there as well - especially since the car will be dropped 2". Because I have fender flares I want to fill out the fenders, but prefer not to have to cut, roll, or notch. It seems that every project leads to breaking out the torch, grinder and welder :smile:

If anyone can help out with these questions, and also have photos, please let me know.

F (2" drop) 17x8 4" bs with 245/40/17 or 245/45/17
R (2" drop) 17x9.5 4.75" bs with 285/35/17's

Will these scenarios work with or without additional mods?

I am new to the boards and want to say that I have gained a ton of knowledge from them. Thanks

How are you planning to drop the rear 2"? I think the lowest you will find will be BellTech springs that will drop the car 1.5". As far your tire size goes, you will be fine running a 4.5" backspace with the 285's. You can actually get a little wider tire under there but if you are dropping 2", you might just want to stick with the 285's. I am currenting running 315's with an 1.5" drop on a 10" wide rim with 5.5" backspace. I am needing to frame notch though. I will be running LS1 rear discs which help push the wheel out a little but i havent got that far yet!

 

[rk87gnnj]

Intrax springs. Guess what though? I thought they had an advertised drop of 2" in front and 1.8" rear, but I just checked their website to find that its actually 1.5"F and 1.2"R which is fine. Thanks for questioning me on that. I was havings buyers remorse thinking I went overboard in lowering it too far. Sometimes I go overboard with things and wind up creating more projects for myself. Do you think I will have to trim the fenders with the 285's?

 

[jdpolzin]

Yeah I have seen the Intrax springs and they do advertize a 1.8" drop but i have also heard the springs are the exact same spring as the BellTechs. I dont see any reason for trimming with the 285's. A buddy of mine runs 305's in the rear with 10" wide wheels and has no modifications to the body or frame.

 

[rk87gnnj]

Thanks. I really appreciate your help in clearing this up for me. It makes deciding what to buy that much easier.

 

[jdpolzin]

Not a problem, glad to help!!!!!

 

[jhanson1750]

Not trying to rob your thread but any pics of the 305's close up on the back (frame to tire) and front (lip to tire). I sure would like to see this as that is going to be my next major move once I get through christmas (yes CHRISTmas) and get my motor back together. Thanks so much Jon Hanson

 

[fgordon]

29.5x13.5x15 w/7" BS :smile:
or
28x10.5x15 w/4.5" BS

Seriously, I think most of our cars will accept a 4.5" BS on a 15" wheel. I have a set of 275x50x15 BFG DR's on a set of 15x10's w/4.5" BS that fit my 84 before the back-half surgery. (Fenders were rolled)

 

[Steve87GN]

Well, ummm, not to be rude, but what about with my setup (as I initially posted at the start of the thread)? I'm not going to be running the fender flares nor am I lowering the car, just installing new springs from Kirban front and rear. Can I get away with a 285 in the back as well? Would I need a 4", 4.25" or 4.5" backspacing? Thanks guys.

 

[jdpolzin]

Go with a 4.5" backspace!! Pretty universal BS for our cars on stock springs. You will fit the 285's just fine!

 

[53dogg]

I'm no expert,but I have 17 X 8 tt IIS with 245/45s all the way around Car is dropped an inch,no rubbing issues except on a deep bounce.picture in members rides

 

[jdpolzin]

I'm no expert,but I have 17 X 8 tt IIS with 245/45s all the way around Car is dropped an inch,no rubbing issues except on a deep bounce.picture in members rides

Any pics?

 

[53dogg]

Any pics?

click on photo gallery,then member's galleries for a pretty decent shot of car,HTH

 

[rk87gnnj]

53doggy,

The chrome accents on the car work well with the polished wheels. I'll probably powder coat my centers black. Your car appears to have been lowered. If so,how far did you lower it?

 

[Steve87GN]

Go with a 4.5" backspace!! Pretty universal BS for our cars on stock springs. You will fit the 285's just fine!

Great, thanks for the help dude.

 

[53dogg]

rk87,1 inch in front,maybe .8 in the rear,just wanted to close the gap a little and leave room for some 275s in back,when I can afford them!!

 

[ds4545]

I run 17 X 9.5 American Racing Torque Thrust with 4.5 inch back spacing with no problem.