Team Camaro Tech banner

1 - 11 of 11 Posts

·
Registered
Joined
·
84 Posts
Discussion Starter #1
i'm going crazy trying to make sure i figured out the correct BS/tire size.
can someone please confirm this is the right set up?

car:
68 vert
baer brakes up front and disc in the rear
hotchkis suspension all around

wheel specs:
FRONT:
5 X 4.75 bolt pattern
17X8 wheel
4.75 back spacing
235-45-17 tire size

REAR:
5 X 4.75 bolt pattern
17X9.5 wheel
5.5 backspacing
275-40-17 tire size

going to go with the Billet Specialities Street Star wheels.

i hope this works...i looked at a few threads and this seems to be the correct BS for the size...but i guess i'm just paranoid and i would like to triple check that it is correct.

Thanks!
 

·
Registered
Joined
·
84 Posts
Discussion Starter #3
you are 1 size bigger than me on both ends. It will be tight but should fit. Measure the back and make sure the rear is centered in the car, many are not. B/s - width numbers look good
thanks for the heads up Jim. I wish they had a 8.5 width but they don't. it goes from 8 to 9.5. I wanted a wider wheel for the rear so i pretty much had to go with 9.5 rear.

is the tire size correct or should i run a narrower tire in the rear?
 

·
Gold Lifetime Member
Joined
·
3,360 Posts
That should be the perfect setup. Might have a tire rub a bit in the rear turning into some steep driveways, some have others haven't. I'd go for it.
 

·
Premium Member
Joined
·
22,122 Posts
I'd go for it too, after some careful measuring.

The only times I've had 275's on my car:

Hoosier quicktimes on 15x7 second gen stock rims, this are big bulbous tires, and the right rubbed the inside of the inner fender. Note my rear was offset 1/2" at that time.

ET Streets, also on 15x7 second gen rims. No where near as bulbous as the hoosiers. I don't think they rubbed, but they were not on the car long, one trip from the parking lot thru the staging lanes to the line, at which point excessive traction caused the driveshaft to violently exit the vehicle.

I need to replace at least my fronts, and it's got me wondering if I dare put a 40 series 275 on an 8" rim? New rear is only off 1/4" so I'm pretty sure they would fit ok.
 

·
Registered
Joined
·
84 Posts
Discussion Starter #6
I'd go for it too, after some careful measuring.

The only times I've had 275's on my car:

Hoosier quicktimes on 15x7 second gen stock rims, this are big bulbous tires, and the right rubbed the inside of the inner fender. Note my rear was offset 1/2" at that time.

ET Streets, also on 15x7 second gen rims. No where near as bulbous as the hoosiers. I don't think they rubbed, but they were not on the car long, one trip from the parking lot thru the staging lanes to the line, at which point excessive traction caused the driveshaft to violently exit the vehicle.

I need to replace at least my fronts, and it's got me wondering if I dare put a 40 series 275 on an 8" rim? New rear is only off 1/4" so I'm pretty sure they would fit ok.
is there a correct way to mesaure how much offset is the rear axle?

or do i just measure it to the body and go for a rough estimate?
 

·
Premium Member
Joined
·
22,122 Posts
is there a correct way to mesaure how much offset is the rear axle?

or do i just measure it to the body and go for a rough estimate?
I just put straightedge on the hub and measured from it to the inner wheelhouse, as well as to the outer.

A lil math from there to figure your biggest tire size and wheel offset.

Offset needs to be ~ half the difference, a-b/2. Back in the old days (lol) we used offset rather than backspace. For you young guys, an 8" rim with 4" backspace would be zero offset, with 4 1/2" backspace would be 1/2" offset.

1/2" sidewall to inner fender is an absolute minimum, and will do some scraping when one wheel goes "up" but the other doesn't, such as turning into a driveway and going over the curb one wheel at a time. 3/4" - 1" inside clearance is better.

Outside can be quite a bit tighter, unless the car is very low. Hitting a bump with one wheel tends to tuck that wheel in, away from the outer lip.
 

·
Registered
Joined
·
84 Posts
Discussion Starter #9
finally got to do some measurements in the rear...

from the lip of the quarter to the inner wheel well it's about 11-1/4 inches.
from the hub to the inner wheel well it's 7 inches
passenger side hub to outter qtr lip 4-1/8
driver side hub to outter qtr lip 4-3/4

the sectional with of a 275 is around 11 inches...i'm thinking that the rear is too wide. the 5.5 back spacing looks to be ok since i have 7 inches from the hub to the inner well.

so i guess i'm going to be looking at 255 45 17 for the rears. will there be enough sidewall protection for the rim or is it a lost cause on a 45 profile tire?
 

·
Premium Member
Joined
·
22,122 Posts
The 255 sounds like a wise choice.

Many tires these days have "rim protectors" built right onto them. The area right above the bead protrudes over the edge of the rim. My goodyears are like that.
 

·
Registered
Joined
·
657 Posts
so i guess i'm going to be looking at 255 45 17 for the rears. will there be enough sidewall protection for the rim or is it a lost cause on a 45 profile tire?
You are actually going to have more sidewall with the 255/45 over the 275/40. The 255 is a little taller. I think you will be happy with the way the 255/45 looks on the 9.5 wheel. It's hard to tell the difference when they are mounted on a wheel that wide.
 
1 - 11 of 11 Posts
Top