Rearend housing length.

[Camaro96]

Thank you for your opinions in advance.

Trying to figure out what length of Rearend needs to be to run a true 10.5 tire with out tubing the car or making quarters panel adjustments. On 96 Camaro if the stock one is 60 inches. Would a 56in be to short.

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[Injuneer]

Depends on the wheels, specifically offset/backspace.

I have a stock 4th Gen length Strange 12-bolt, 15x10” 7.5” backspace Weld Pro-Stars, and have run a Hoosier QTP 26x10.5-15 (see signature photo below) and an M/T 28x10.5-15W (10.9” tread, 13.1 section width).

Inner fenders were hammered slightly for my street tires - 315/35-17 BFG Drag Radials, on 17x11 50mm offset ZR1/GS wheels.

No tubs, no quarter panel mods, nothing beyond hammering the inner fenders and rolling the fender lip. All tires fit within the wheel wells, not outside the fender. The 28” tire needs to be carefully centered in the wheel well to avoid contacting the leading edge of the wheel opening, or the leading edge of the bumper cover (at least on a Pontiac) when the tires grow at speed - only a problem with non-radials.

[Camaro96]

Depends on the wheels, specifically offset/backspace.

I have a stock 4th Gen length Strange 12-bolt, 15x10” 7.5” backspace Weld Pro-Stars, and have run a Hoosier QTP 26x10.5-15 (see signature photo below) and an M/T 28x10.5-15W (10.9” tread, 13.1 section width).

Inner fenders were hammered slightly for my street tires - 315/35-17 BFG Drag Radials, on 17x11 50mm offset ZR1/GS wheels.

No tubs, no quarter panel mods, nothing beyond hammering the inner fenders and rolling the fender lip. All tires fit within the wheel wells, not outside the fender. The 28” tire needs to be carefully centered in the wheel well to avoid contacting the leading edge of the wheel opening, or the leading edge of the bumper cover (at least on a Pontiac) when the tires grow at speed - only a problem with non-radials.Thank you Injuneer for the information. I'm ponduring mini tubs to see how large of tire I can get under the car with out modifying the wheel well or rolling the fender.

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[Injuneer]

Curious... how are you going to install mini-tubs without modifying the wheel well? And by "rolling the fender lip" I meant simply bending upwards the sharp inner lip that projects inward toward the tire sidewall.... totally invisible.

Sorry I couldn't help. Maybe someone else will better understand your question.

[Camaro96]

Curious... how are you going to install mini-tubs without modifying the wheel well? And by "rolling the fender lip" I meant simply bending upwards the sharp inner lip that projects inward toward the tire sidewall.... totally invisible.

Sorry I couldn't help. Maybe someone else will better understand your question.I would agree with you. I have to modify wheel well. I will remove the factory ones and place in New one and make the hatch area smaller. And most likely do away with the spare tire compartment. I just did not want to modify the out side wheel by rolling the lip. For wanting to add boost. From building the engine to handle it is all. Then it the other components that need beefing up transmission, Rearend.

With that being said. injuneer I would like your thoughts on shorting the axel tubes by 2 inches on each side.
Injuneer I thank you for sharing your thoughts and knowledge.

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[Injuneer]

I don't think I understand your goals, guess I missed the point. I haven’t the slightest idea why you think you need to shorten the axles to fit a 10.5” tire. Maybe someone else smarter than I am can figure it out.

[Camaro96]

I don't think I understand your goals, guess I missed the point. I haven’t the slightest idea why you think you need to shorten the axles to fit a 10.5” tire. Maybe someone else smarter than I am can figure it out.I was able to pick up a 9in housing, 40 spline axles, after market LCA, pan hard bar, torque arm and mini tubs for a real good deal for 4 gen Camaro that is 56in from plate to plate. Standard length is between 60- 61" plate to plate

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[Camaro96]

[QUOTE=Injuneer;484802]I don't think I understand your goals, guess I missed the point. I haven’t the slightest idea why you think you need to shorten the axles to fit a 10.5” tire. Maybe someone else smarter than I am can figure it out.[/QUOTE Injuneer: the question I have is can I run a 4in shorter rear end housing and still use a stock backspace wheel? With out mini tubing?

I what to run 315/60/15 tire and have it tucked under the car without having to modify the quarter panels, or am I going to need to run 275 tire size ?

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[Injuneer]

The issue in not the width of the tire, or the width of the axle. Using a wheel with less offset makes up for a narrower axle. The problem is the huge diameter of that tire.

A 315/60-15 is a 29.9” diameter tire. Anything over 28” is a problem. Stock is 26”. Why do you need a tire that large. The only 4th Gen F-Body I've ever seen with a tire that big was making 1,350 HP and running low 8’s. I've got a 28” bias-ply slick, and had to cut back the leading edge of the flexible bumper cover, because the tire was growing enough at 130 MPH that the bumper cover was hitting the tread.

You can tuck the wheels in more to keep the tire completely inside the outer fender, but now they are going to rub the inner fender (yes, then you may need a mini-tub with a 315 tire) and may even hit the lower control arms. A tubular LCA can be offset to give a bit of extra room.

Also makes a difference whether it’s a radial or bias-ply tire, because of growth of a bias-ply tire at high MPH.

Can you get by with a 28” diameter radial? The weight of a 29.9” tire is going to eat up rear wheel HP. Then there's the issue of rear axle ratio with a 29.9” tire.

I don’t know enough about your car to understand your goals.

[Camaro96]

[QUOTE=Injuneer;488104]The issue in not the width of the tire, or the width of the axle. Using a wheel with less offset makes up for a narrower axle. The problem is the huge diameter of that tire.

A 315/60-15 is a 29.9” diameter tire. Anything over 28” is a problem. Stock is 26”. Why do you need a tire that large. The only 4th Gen F-Body I've ever seen with a tire that big was making 1,350 HP and running low 8’s. I've got a 28” bias-ply slick, and had to cut back the leading edge of the flexible bumper cover, because the tire was growing enough at 130 MPH that the bumper cover was hitting the tread.

You can tuck the wheels in more to keep the tire completely inside the outer fender, but now they are going to rub the inner fender (yes, then you may need a mini-tub with a 315 tire) and may even hit the lower control arms. A tubular LCA can be offset to give a bit of extra room.

Also makes a difference whether it’s a radial or bias-ply tire, because of growth of a bias-ply tire at high MPH.

Can you get by with a 28” diameter radial? The weight of a 29.9” tire is going to eat up rear wheel HP. Then there's the issue of rear axle ratio with a 29.9” tire.

I don’t know enough about your car to understand your goals.[/QUOTE Injuneer: I wanted to put as much tire under the car as I can get and when I calculated the rear end gear the 29.9 in tire help manage rpm during Hwy driving.

As for more information on the car it is currently the plan is this winter to drop in a built 385 with AFR 227 what have been worked with a sold roller cam with cam specs in the neighborhood 650/650/110 ( I don't remember the exact specs and the cam card is in storage. D1sc procharger with 3.7 pulley with intercooler air to air by procharger chart 12.7 #of boost Will have Rossler 4L60E with 3800 stall upgraded suspension have a Fab 9 housing the is 56in in length with 510 or 456 gears tuned pcm by Moehorsepower meth injecton.


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[Injuneer]

I can do the theoretical math, but I have no direct experience with a 30" diameter tire, other than seeing what a friend had to do with a 30.5" ET Drag (bias-ply slick) to get it to fit on his 30th SS Camaro. He had to cut back the sheet metal on the edge of the quarter panel in front of the tire, and cut back the bumper cover (and the sheet metal behind it). He also had to open up the inner fender liner. If he had simply tried to move the tire 2" deeper into the wheel well, I'm pretty sure the tire would be hitting the lower control arm, and the rear suspension would have to be modified somehow to clear the tire. Plus it would have looked really odd with the tire sunk way inside the fender.

Hopefully, someone that has actually put a tire that size on a Camaro can help you. It's impossible for me to give you a precise answer without actually looking at the setup, the wheel, the tire, the rear axle assembly.

You need to understand that the width of the rear axle assembly is not the only thing that determines where the tire sits in the wheel well. The other factor is the offset of the wheel. Stock wheels have roughly a 2" positive offset. If you narrow the stock rear by 2" on each side, you need wheels with a 0" offset to keep the wheels in the same position.

You also need to reference the points on the axle assembly where you are measuring 56" wide. The stock rear is 61-3/4" measure from the outer face of the wheel mounting (axle) flanges.

[Camaro96]

I can do the theoretical math, but I have no direct experience with a 30" diameter tire, other than seeing what a friend had to do with a 30.5" ET Drag (bias-ply slick) to get it to fit on his 30th SS Camaro. He had to cut back the sheet metal on the edge of the quarter panel in front of the tire, and cut back the bumper cover (and the sheet metal behind it). He also had to open up the inner fender liner. If he had simply tried to move the tire 2" deeper into the wheel well, I'm pretty sure the tire would be hitting the lower control arm, and the rear suspension would have to be modified somehow to clear the tire. Plus it would have looked really odd with the tire sunk way inside the fender.

Hopefully, someone that has actually put a tire that size on a Camaro can help you. It's impossible for me to give you a precise answer without actually looking at the setup, the wheel, the tire, the rear axle assembly.

You need to understand that the width of the rear axle assembly is not the only thing that determines where the tire sits in the wheel well. The other factor is the offset of the wheel. Stock wheels have roughly a 2" positive offset. If you narrow the stock rear by 2" on each side, you need wheels with a 0" offset to keep the wheels in the same position.

You also need to reference the points on the axle assembly where you are measuring 56" wide. The stock rear is 61-3/4" measure from the outer face of the wheel mounting (axle) flanges.I haven't purchased the 315/60/15 drag radial yet. With what you are saying it looks like I would be safer to run 275/60/15 so that I don't have clearance issues with the bumper cover.

The reared is 56 in from flang to flang and then with the axals installed it is the old big ford brake syle and if I understand correctly that will add 2 3/8 in to each side since I have pro stars that are stock b.s. will I need to change the b.s. on the wheels to make this combination to work ?

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