wtf with the backspacing? need advise please!!

[gofastr]

so people are telling me that I should have 15x8's in the back with 4" backspacing for the cragar street stars that I want, and 15x7's up front with 3.5" backspacing. The only available is
4 1/8" backspacing for both! Are these gonna be ok?

 

[Jimn8or]

The fronts in this backspace might work...As far as the backs go..hmmm... I figure they're gonna rub on the frame [tires will] on absoutely every friggen corner you make. Do the wheels come in 3 1/2" bs? If not, choose another wheel dude.
Jim

 

[UNGN]

Use a 1/4" spacer and they will work fine, even with 275 wide tires.

 

[49-blues]

kirbans gnx wheels were 16x8 with a 4.125 backspacing and didnt rub anywhere.front or back-i ve used 4.5" bs in the rear with 275x60x15 with no problems.

 

[Intercooler]

I have 4.5" BS Stars on my car. I have some pics on one of these threads showing clearance. If your rear is centered you will be okay. If not you will need a 1/4" spacer to be safe.

 

[UNDRPSI]

My car must be different then because the wheels on my car have a 5.25 bs w/275 on them and they never rub!

 

[Roger]

UNDRPSI, If 5.25bs ain't rubbing the frame, you either have 10" wheels or a huge spacer or you'e using a fishermans ruler. What is your secret? with the rubbing problems I've had with aftermarket wheels, I gave up & went back to stock TR wheels.

 

[Red Regal T]

NO WAY ON THE 5.25" BACKSPACE. YOU HAVE YOUR NUMBERS WRONG.

 

[Steve Wood]

4.0 to 4.375 has worked for me with 275s.

 

[UNDRPSI]

OK I guess I am an IDIOT that can not read a tape measure. The wheels are custom made TTII's (which I still have the order form for) 17x9.5 w/ 275 40s. I measured the car VERY carefully per American Racings instructions. They are EXTREMELY close to the frame but DO NOT rub the frame not the unmodified fender well. It is all that the wheel well will hold unmodified. As soon as the engine is back in the car I will be ordering a 17x11 which should fit with the frame notched. I am not trying to flame anyone up or misslead anyone with bogus information. I am just telling you what is on my car and that it works for me. I have several pics if you doubt what is on my car I will e-mail them to you.

 

[Steve Wood]

but, you have 9.5" wheels rather than the 8" that was being discussed...makes a difference.

 

[matt87]

even so a 17" rim with a 40-45 series tire on a 4" b/s wont rub, no side wall flex. a 15" with a tall 28" slick flexes alot and may rub with the same b/s.

 

[charlloots]

i have 8.5 centerline autodrag with 3.5 backspacing 28x12.5 et streets with no spaces and the lips are not rolled in the front 5.5 centerline 3.5 bs mt sportsman 7.0 x 15

 

[UNDRPSI]

I understand how the diff in a 15 and 17 can make a diff considering sidewall flex. However I do not understand how BS differs between a 8" or a 9.5" wheel as bs is the maximum allowable distance between the hub and the frame or closest contact point depending on tire diameter. If I were going to order the same wheel that is on the car only in an *' version I would not order the same bs due to how close it is to the frame. It also would sit to far under the car. I guess that is what you were referring to when ytou suggested that the wheel size made a difference.

 

[fireberd350]

so you cant go wrong with 3.5" backspacing? im soon going to order some weld draglites 15x8 and 15x7....and 3.5" BS is the way to go?

 

[UNGN]

Originally posted by UNDRPSI
However I do not understand how BS differs between a 8" or a 9.5" wheel as bs is the maximum allowable distance between the hub and the frame or closest contact point depending on tire diameter. If I were going to order the same wheel that is on the car only in an *' version I would not order the same bs due to how close it is to the frame. It also would sit to far under the car. I guess that is what you were referring to when ytou suggested that the wheel size made a difference.

Wheel width matters when determining the proper backspacing.

A 275mm wide tire on a 9.5" wide wheel will have less sidewall bulge than it would on a 8.0" wide wheel. It' the sidewall bulge that rubs, not the wheel lip.

A 275mm wide tire on a 7" wide wheel, with 4.5" backspacing will rub the frame bigtime. A 275mm wide tire on a 9" wide wheel, with 4.5" backspacing won't rub the frame at all.

 

[Ormand]

Back Spacing..

Back Spacing is defined as "The distance from the inner edge of the wheel to the hub mount pad" So, yes, the backspacing is a big factor in whether or not the tire will hit the frame, regardless of the wheel width. The wheel width, though, will affect whether the tire hits the fender lip. From reading these posts over the years, I've concluded that no two Regal bodies have the same clearance, and that very few have the same clearance on the left and right sides. Bottom line- MEASURE! There was a neat article in "Hot Rod" or one of those mags a few years ago, on how to measure using a piece of wood and a section of all-thread. The piece of wood has a couple holes, so you can slip it over the lug studs, and another hole, out at the end, with the all thread. You turn the thing around, and measure clearance, inboard and outboard, the write it down. Now you KNOW that you have six inches, or whatever, from the face of the axle flange to the outside of the frame, and you can plan/buy based on the actual dimensions.

 

[qwknuf6]

I will add,since I just yesterday changed from a 16x8 wheel 4" BS to a 16x9.5 wheel with 5" bs , I thought there was no way the 5" bs would work since the 16x8" wheel w/4"bs was very close to the frame .
With the same tire (255x50x16) the 16x9.5 w/5" bs was no closer to the frame than the wheel w/4" bs

I think a 5.25 bs would work .

Now for max size slick you NEED to have 4" to 3.75" bs ,you can fit a 28x10.5 et drag with that bs on 8" wheel