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Discussion Starter · #1 ·
This might be a good read and/ for a Sticky for the Wheels & Tires Forum

Every car is different from Driver Side to Passenger Side
and taking measurements of your car's Rear Wheel Wells etc
is the key to what Wheel / Tire Combo size will fit without rubbing or hitting anything ;
BACK SPACING & WHEEL WELL / Shock Mount Room https://www.rsracing.com/tech-wheel.html
First measure with the current sized Wheels/Tires on the Car ;
1.Wheel’s Rim room inside curved lip of Wheel Rim to bottom part of Shock Nut =
This is because as you increase the Back Space on a Wheel
and or increase the Width of the Wheel it may interfere with the Lower Shock Mount/Bolt
2.SPACE from Front of Fender Well to front of current tire when mounted to rear end this is for to measure the MAX height/diameter a tire can be as it is Important that you allow Bias tires a growth margin .

Second with the Wheels/Tires removed from Both DR & Pass sides, one side at a time or all same time
measure the following;
A. Rear End Width – Face of Rear Brake Drum/Disc Driverside to Face of Drum/Disc Passengerside = ??“
B.OUT SPACE from inside Lip of outside Fender to Face of Rear Drum/Disc Brake Hub/Wheel Mounting Pad
................. DR Side = ??“ .... PASS Side = ??”
C.IN SPACE from Face of Rear Brake Drum/Disc Hub/Wheel Mounting Pad to Frame/Inner Fender
................. DR Side = ??“ .... PASS Side = ??”
D.Total Wheel Well Space = # 2 + # 3 measurements #s
................. DR Side = ??“ .... PASS Side = ??”
if one side is less then use it as the applicable number
or make sure the Rearend is centered properly

Important things to NOTE;
1. the Rear Lower Shock Mount Bolt may interfere with the Wheel’s Rim
2. and yes your car's exhaust may interfere with the Tire on a 10" Wide Wheel
3. Type of Brake system on rearend, Drum or Disc ! as the Disc setup is usually wider than a Drum setup
4. Is Rearend centred ?
5. Has the car been Lowered ?
6. Side Wall/Section Width of the Tire = ?
7. Diameter Height of Tire = ? Note to make sure a to High of a Diameter Tire is not used ;
Measure from the Centre of the Wheel towards the Front of the Car to the Body behind the Door
to see how much Space there is = ?? X 2 = for the Max Diameter Tire to use LESS a little ! EG. 14.5” x 2 = 29” Max = 28”
8. Size of Wheel you wish run ?

Measure twice and you will only need to buy once the Wheels/Tires Combo
you want to fit within your car’s Wheel Wells .

Here is an Example ;

My 67 Chevelle with a 60” Wide Rearend
Car's Wheel Well Measured Total Wheel Well Space = 13"
This is based on the following;
B. Measuring from the Face of the Drum Brake on a 60" Wide Rearend OUTward to the Innerside of the Fenderside = 5.92" OUT Space
C. Measuring from the Face of the Drum Brake on a 60" Wide Rearend INward to the Frame = 7.08" IN Space
D. B.# + C# = 13” Total Wheel Well Space
E. Just to Double Check, Measure from the Fender Inner lip to the Frame/Inner Fender = 13"

So here is the cal for my Car's Wheel Well to see what is the Best/Biggest Wheel / Tire Combo to Fit without any Rubbing etc. ;
Out Room from Fender Lip to outside Tire Side Wall and inside Tire Side Wall to Frame IN Room

Wheel 8“ Wide with a 4.5” Back Space
a. the portion of it towards the OUTside / Inner Fenderlip = 3.5" = 43.75%
b. the portion of it towards the INside/Frame = 4.5" = 56.25%


Tire Mickey Thompson ET Street S/S Radial Tire P275/60R15 = Dia 28.2"/ Tread Width 9.3"/ Side Wall Width 11.1"
Max OUTspace 5.92” 1.07” = Room To Tire Sidewall from FenderLip 4.85” outward TIRE inward 6.25” Room from Tire Sidewall to Frame = .83” Max INspace 7.08”

Wheel 10 “ Wide with a 5.5” Back Space
a. the portion of it towards the OUTside / Inner Fenderlip = 4.5" = 45%
b. the portion of it towards the INside/Frame = 5.5" = 55%

Tire Mickey Thompson ET Street S/S Radial Tire P295/55R15 = Dia 27.8"/ Tread Width 10.6"/ Side Wall Width 12.2"
Max OUTspace 5.92” .43” = Room To Tire Sidewall from FenderLip 5.49” outward TIRE inward 6.71” Room from Tire Sidewall to Frame = .37” Max INspace 7.08”
 

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66 El Camino 57 Chevy pickup 2004 Tahoe
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Stuck to top by Tom 2pm MST 7-18-20

Thanks to Greg for taking time.
 
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There always seem to be a lot of questions about the wheel & tire sizes that fit a particular year rear end. A few years ago I went thru this on my 70 Chevelle. I got it on the lift & measured every thing in the rear axle area.

Since 70 thru 72 are the same body style his drawing should apply apply to all 3 years. For other years while the dimensions will probably change, you can see what you need to measure for your particular year.

Hope this helps.
 

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Discussion Starter · #4 ·
Thanks Roman
Great Pic/Drawing
 

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Discussion Starter · #5 ·
This may or may not help with the FRONT Wheel/Tire Combos

On BOTH sides of your Car's Front Wheel Wells

1. Measure the Height Room you have from your current Wheel/Tire Combo at Full Turn
Top of Tire to the Wheel Well Underside Fender Lip
Driverside = ??" ///// Passengerside = ??"
2. Measure any Width Room between the Tie Rods/Frame Suspension Parts and the Side of the Tire
Driverside = ??" ///// Passengerside = ??"

If using the same Wheel Diameter / Width / BackSpace then just Compare
the New Tire's Width difference with your Old Tire's Width = ??"

Compare the Differences of your Current Tire Height and Width
with the New Tire Height and Width
Divide by 2
EG. Height - 26" less 28" = 2" / = 1" Room needed at the Top plus allow for some Upward Suspension Movement
if/when you hit a Bump, Curb or Pot Hole
EG. Width - 7.9" less 6.9" = 1" / = .50" Room needed at Side of Tire to not Rub on Stuff
also allow for Side Wall Flex when driving and Turning at Max
 

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There always seem to be a lot of questions about the wheel & tire sizes that fit a particular year rear end. A few years ago I went thru this on my 70 Chevelle. I got it on the lift & measured every thing in the rear axle area.

Since 70 thru 72 are the same body style his drawing should apply apply to all 3 years. For other years while the dimensions will probably change, you can see what you need to measure for your particular year.

Hope this helps.
Sweet thanks man!
 
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