Author Topic: 15 x 8 Backspacing question  (Read 6269 times)

Olympic gold

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15 x 8 Backspacing question
« on: May 29, 2019, 11:37:36 PM »
Would a set of 15 x 8 rear wheels with a 5.5 backspace work on a 1969 Camaro? 
also, does anyone have problems running a 15 x 3.5 wheel in the front? How much would such a small tire affect braking?   

x66 714

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Re: 15 x 8 Backspacing question
« Reply #1 on: May 30, 2019, 01:10:26 AM »
Braking is caused by friction, not just friction of the brake pads/shoes but by how much tread is on the ground. Over the years I've seen lots of cars slide, especially when they have to use their brake in a corner...Joe
See America's First, Chevrolet

1968 Z/28 Corvette Bronze. Black Hounds Tooth. 02E Los Angeles born 3/13/1968 pnt OO. Purchased March 1976
1969 SS396 Yellow/Yellow 08E Norwood born 8/28/1969 pnt 76E. Purchased April 1981

X33RS

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Re: 15 x 8 Backspacing question
« Reply #2 on: May 30, 2019, 03:49:09 PM »
On the front tire deal, we have 2 cars here that currently run pizza cutters on the front.  4" wheels on both of them.  They are driven fairly regularly and have been this way for many years.

One is running the M/T 28x6 street radial tire.   

I can say they drive well enough, turn and stop fine in normal type driving.  Even okay on the twisty mountain roads around here.  A couple of panic stops in the past has locked up the front tires but you have to jump on the brakes pretty hard to do that.  Locking up the rear on these cars might be more of a challenge anyway because we run drag radials on them 100% of the time and they are grippy.  So may not be a fair comparison.  Thousands of street miles like this though and no complaints.  These cars aren't something we go racing through the mountains with on the twisty roads either though.

My daily driver for years was a 71 nova and I had made 4 inch chevy rally wheels back before they were being produced and ran 165/15 VW tires on it.  Drove that car for several years without problems.  Before that I daily drove a 56 nomad with manual steer and manual drum brakes that handled like a school bus so you kind of get used to extra braking distances and slowing for curves, which is probably why skinny front tires don't bother me.

Stingr69

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Re: 15 x 8 Backspacing question
« Reply #3 on: May 31, 2019, 03:37:36 PM »
Had 4" Cragars on the front with VW tires, 10" Cragars on the back with Formula 1 Super Stock Tires.  These old cars handle like Conestoga wagons even with the original tires so just rock the big and little's!!!!

crossboss

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Re: 15 x 8 Backspacing question
« Reply #4 on: June 01, 2019, 01:10:19 PM »
Would a set of 15 x 8 rear wheels with a 5.5 backspace work on a 1969 Camaro? 
also, does anyone have problems running a 15 x 3.5 wheel in the front? How much would such a small tire affect braking?   


You should be ok with that backspacing. Running the 'skinnies' up front will compromise braking, and will most likely cause more nose dive during hard stops, as your 'working' the tires/brakes much harder. The small tread pattern is the enemy here. That said, obviously your not going for any road racing competition, and I assume street and mild drag racing, so you should be fine. Lastly, IF you are using soft front springs with 90/10 shocks, and a loose front sway bar (or none at all) keep this in mind when your street driving and the distance for stopping.
Just another T/A fanatic. Current lifelong projects:
1968 Olds 442 W-30
1969 Mustang Fastback w a Can-Am 494 (Boss 429)

RS Copo

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Re: 15 x 8 Backspacing question
« Reply #5 on: June 02, 2019, 02:23:23 PM »
I ran 9 inch slicks on 15x10,5 inch backspace wheels on my 69 without any issues. If memory serves me correct, I did not have another 1/2 inch of clearance to play with.

Jon Mello

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Re: 15 x 8 Backspacing question
« Reply #6 on: June 02, 2019, 03:30:37 PM »
5.5" backspacing is too much for a Camaro with stock rear wheel wells.
Jon Mello
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X33RS

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Re: 15 x 8 Backspacing question
« Reply #7 on: June 02, 2019, 03:58:10 PM »
Would a set of 15 x 8 rear wheels with a 5.5 backspace work on a 1969 Camaro? 
also, does anyone have problems running a 15 x 3.5 wheel in the front? How much would such a small tire affect braking?   


You should be ok with that backspacing. Running the 'skinnies' up front will compromise braking, and will most likely cause more nose dive during hard stops, as your 'working' the tires/brakes much harder. The small tread pattern is the enemy here. That said, obviously your not going for any road racing competition, and I assume street and mild drag racing, so you should be fine. Lastly, IF you are using soft front springs with 90/10 shocks, and a loose front sway bar (or none at all) keep this in mind when your street driving and the distance for stopping.

Interesting you mentioned that.  Doubt many here bother with that type of thing but we have 4 cars setup very similar.   All of them are street driven.  2 of them are 90/10's up front and a few other suspension tricks for weight transfer and instant center changes.   On the sway bars I hone the urethane bushings so they don't squeeze the bar so tight, then grease them.  Allows front end movement up and down but still helps to control sway a little bit on the street.  I also knock the knurls down on the control arm bushings and install with graphite grease so the arms move a little more freely.  On the nomad I run moroso trick front springs as well and daily drove that car for many years.  Others are more in depth but I won't get into details that most wouldn't be interested in here.

Here's one I have that I run as a pure stock rules car.  No adjustable shocks allowed so I run old oil filled shocks that move more freely, and other suspension tricks I mentioned above.   It's gone 1.89 60 on stock F70-14 bias plies.  I also drive this car daily and it's a fantastic handling and driving  car despite the suspension mods.

https://youtu.be/er1z7PpqsnY

https://youtu.be/8r8hzS-iZP0

https://youtu.be/bavv6KgUcmw

Olympic gold

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Re: 15 x 8 Backspacing question
« Reply #8 on: June 03, 2019, 06:34:22 PM »
From what I have read I am going to pass on the 5.5 backspacing wheels but may see if I can still get the skinnies.

joesauer

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Re: 15 x 8 Backspacing question
« Reply #9 on: June 04, 2019, 04:39:24 PM »
I'm running 15 x 8 inch Cragar rims with 4.5 backspacing, 215/70R15's on the rear of my 68.  Stock height suspension.  All is ok with that setup.  Suggest you don't go past that.  Think the 5.5 backspacing might rub the fender lip on high speed cornering.  Depends on the tire also.