BACKSPACING AND OFFSET FOR THE WIDEST TIRE ON THE REAR.

Toddmc66

Import punisher.
I'm buying new wheels and tires. My frame (isn't notched). I'd like to put a 305 on the rear. I've seen other post saying they have 305's on the rear but never post what the backspace or offset is. Did some research and so far I've found for a 295 to 305 the backspace is 4.5" on a 10" wheel. Anyone have any experience with this or have 295 or 305's on their car ? if so what wheels and specs. Any help would be appreciated.
 

NOONG

Member
I have a 295 with a 10” wheel with a 4.5” BS and that’s as wide as I could go without notching my frame. I did have to roll my fenders though. Pics with a stock type wheel and a drag wheels.



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Turbo6inKY

Short Guy
That close to the limit and you're going to have to measure. Whether or not a 305 fits in lieu of a 295 and what backspace really is going to depend on how your car made it out of the factory.

And you will have to roll the fender lip.
 
Never heard of a 305 fitting without a notch. I used to have a 295 and those still rubbed my frame but I did roll the fenders.
 

Toddmc66

Import punisher.
Thanks for the responses. I'll have to measure and see where I'm currently at. The fenders are rolled.
 

Turbo6inKY

Short Guy
If you go through this worksheet, it'll get you all the measurements you need to know what will fit on one piece of paper.

https://4aah2h38qz0d1pp9jb46vzfw-wpengine.netdna-ssl.com/wp-content/uploads/2017/04/find_the_largest_tire_and_wheel_combo_for_my_vehicle.pdf

Going as big as you want, you likely will end up having to order a custom wheel with the right backspace to get the rubber under the car, and it's going to be tight.

If you don't have a lateral location device like a panhard or watts, you'll want one to keep the axle centered while it's operating.
 

NOONG

Member
Fitting and fitting with airbags aired up are two different things. Over the years Ive seen countless people say there rim fits and doesnt rub and the dam air bags air pumped up to keep the body off tires
I forgot the day my airbags are aired up as well! Thanks for reminding me @turbonasty


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dynoman

Well-Known Member
My car has fenders rolled & frame notched . I tried 295/65/15 MT DR's on my car and they would rub slightly on a sweeping turn with bumps . The 295/65/15's are a 30" tall tire and the 295/55/15 is 28" . I'm guessing you are talking about the 55 because there is no room to fit a 65 without a notch and massaging the wheel tub with a sledge hammer . I am talking about fitting with NO air bags and the car sitting down over the tires like it's suppose to .
My wheels are 15x10 4" backspace , but my rear end is narrowed 1 1/2" each side so that would be like a 5 1/2" backspace as far as where the tire would sit in the wheel well on a stock width rear end .
These are pictures of the 295/65/15 mounted and one of a comparison of a 295/65/15 @ 30" tall & 275/60/15 @ 28" tall .
DSCN0600.JPG
DSCN0601.JPG
DSCN0603.JPG
 

Toddmc66

Import punisher.
If you go through this worksheet, it'll get you all the measurements you need to know what will fit on one piece of paper.

https://4aah2h38qz0d1pp9jb46vzfw-wpengine.netdna-ssl.com/wp-content/uploads/2017/04/find_the_largest_tire_and_wheel_combo_for_my_vehicle.pdf

Going as big as you want, you likely will end up having to order a custom wheel with the right backspace to get the rubber under the car, and it's going to be tight.

If you don't have a lateral location device like a panhard or watts, you'll want one to keep the axle centered while it's operating.
Thanks for the measurement sheet.
 

scot w.

GNSperformance.com
You know, There really isn't a "Magical" wheel size that fit's All... Although wheel sizes and BS stay the same "Tires" and their sizes Do Not! Each tire manufacture tire size actually vary to some degree, you can take 3 of the exact same tire size from three different tire manufactures and the width will be different on all three... For example: I ran a 285/35-18 Toyo proxis T1R and then went to the same size but a BFG KDW2.... the Toyo proxis was wider on the same exact wheel than the KDW2 was... So when I seen that the BFG tire was narrower I went ahead and bought the 295/35-18 and it fit great on a 10" wheel all I had to do was roll the lips....
DSC_0147.JPG
 

Toddmc66

Import punisher.
I purchased the factory replicas from Gbody Parts. I purchased the 10x15 with 4.5 back space. Has anyone put a 295/60/15 or any other 275 combination on this particular wheel? if so what brand?
 

SpeedRacerX

Well-Known Member
I purchased the factory replicas from Gbody Parts. I purchased the 10x15 with 4.5 back space. Has anyone put a 295/60/15 or any other 275 combination on this particular wheel? if so what brand?
Mickey Thompson ET Street SS 295/55-15, 28" tall, on that exact gbody rim. No frame issues. Newer springs and shocks fyi. Rubbed on fender lips on heavy bumps. Rolled the fender lips and problem gone. I have airbags but I no longer need them since I rolled the lips.



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