Placing a wheel order tomorrow...need to verify my measurements!

[69TAPoser]

'69 Firebird. I am looking to go as wide as possible without rolling the lips.

Front: Stock subframe, stock spindles, GW upper and lower tubulars, QA1 coil over shocks. Wilwood Dynalites.

Rear: Ford 9" (a bit shorter than stock at 52" inside backing plate to inside backing plate). NOT mini tubbed, stock staggered shock locations. DSE 3" drop leafs. Wilwood Dynalites.

I don't have the front fenders on the car to get an accurate measurement, but based on a lot of researching here, it sounds like 18x8 with 4.75" BS will work well on the front?

I have a wheelrite tool that I used on the rear, but I am one of those measure 3x and cut 4x type of guys. According to my messurements, I can fit a 18x9.5 with 3.5" BS on the rear.



Does this sound about right???

Thanks in advance for your input, this is obviously an expensive purchase and I don't want to buy twice!

Phil

[69TAPoser]

Anyone?

Phil

[Budnik Wheels]

Your front sounds fine. The rear is pretty deep. I would just check to make sure that there is no obstruction 5" away from the mounting surface back towards the inside of your car. 5" should cover your 3.5" of backspace plus tire buldge and some room for body roll when cornering.

-jason

[Nine Ball]

Here is what will fit on a stock width rear.

18x8 fronts with a 5.00 bs and 245 wide tire.
18x9.5 rears with a 5.50 bs and 275 wide tire.

If your rearend is narrowed, find out how much shorter it is on each side. Take that increment and subtract it from the backspace on each wheel. So, if the axle is 2 inches shorter on each side, that means your 5.5" bs would then become 3.5" bs.

[EastCoast]

The fronts sound fine.

The rear is hard to say since you have a non-standard rearend width. The samples such as NineBall provided are common with most cars that have typical track widths. The 3.5" of BS on the rear will not work on most cars but in your case, it may. I think you will need to be the judge based on your equipment.

The real question (in my opinion) , if you're trying to measure and spec out your wheels, is how much clearance is needed around things (inside & outside).... I have a post here in the last few days asking this question, but still don't feel that I have any concrete answers on this. I have the wheels and the tires are coming, so I guess I will figure it out....

Good Luck
Robb

PS. I see that NineBall clarified his examples. What he says makes sense on the measuring...

[Josh69]

Here is what will fit on a stock width rear.

18x8 fronts with a 5.00 bs and 245 wide tire.
18x9.5 rears with a 5.50 bs and 275 wide tire.

If your rearend is narrowed, find out how much shorter it is on each side. Take that increment and subtract it from the backspace on each wheel. So, if the axle is 2 inches shorter on each side, that means your 5.5" bs would then become 3.5" bs.

Curious, are you talking Camaro? 1st gen Firebirds have a 1" wider rear axle normally I think, this would alter rear BS by .5" for most.

With is 9" Ford, that's all out the window...but I'm doing the same and either buying a wheelrite or the full on metal tool to figure my '69 firebird out...I really want to run the 18x10" TTII's. I'm rolling the fenders alot before final paint, but not altering the inner fenders from stock.

[Nine Ball]

I'm basing my measurements on a Camaro. I never knew the Firebirds have a wider axle. Can someone confirm this?

[Project69]

Yea the BOP rear axel is a tad bit wide then the Chevy rears. Tried doing a 68 firebird rear swap on a 71 nova and it ended up putting the rear tires into the fender well.

[Josh69]

It was part of their 'Wide-Track' program in the 60's. I believe they are a full 1" wider.

Does anyone know about the front? I'm looking at upgrading my brakes, but no-one seems to know if they are different in the hub or spindle.

I guess the cool part of a Pontiac build...is that there hasn't been eleventy billion built...but that also has it's drawbacks!