Whats the biggest tire that will fit?

Thursday, August 13, 2009 by Ethan Burns

Hello Rodders,

In this installment I’ll discuss rear tire fitment

First think of your tires in terms of a rectangle. Not round as viewed from the side, but height x width as if looking down on the chassis.

All tires will have these two absolute dimensions.

Forget for a minute about P-metric tire sizing, I’ll cover that next time.

How wide is it? And how tall is it?

 

To get a better understanding of what will fit you will first have to measure your wheel wells. No, I’m not going to do it for you. I don’t have the car here, you do.

You will need a plumb bob ( 24”string and a washer tied to it), a tape measure, a ruler or other straight edge (I like to use a carpenters framing square).

For this example I’m measuring the rear of a '69 Dodge Charger with drum brakes.
 

Remove the wheel but keep the suspension loaded if possible. You don’t want to measure with the rear axle hanging down 4 inches further than normal.

 

To find the overall width I’m going to make two measurements and then add them together. These will be useful later when the discussion turns to wheels.
 

Begin by hanging a plumb bob down from the inside edge of the fender lip at the center of the wheel opening. Measure from the now hanging string to the surface of the drum, or what we will call the wheel mounting surface to get the front spacing. . In this example we get around 6 inches. Try moving your string fore and aft and see how the contour of the body brings the fender lip in closer to the drum.


















Consider your tire height and where the sidewall may contact. Be conservative in your estimate and your chances for a perfect fit increase.

Write this measurement down and then proceed to the back spacing measurement.


Using your straightedge lay it across the mounting surface and take a measurement back to the closest obstruction. In this case my measurement is a little over 6 inches at the leaf spring, but it is the inboard wall of the wheel well (about 2 o'clock) that is the closest obstruction at around 5 inches. 

Adding the front width and the backspacing width I arrive at 11 inches. This does not account for clearance! It only serves as the maximum width.

Keeping a half inch of clearance at both the rear and the front we can safely say that a 10 inch wide tire will fit here.

Remember that the section width is wider than the actual tread width. Always go by section width.
We ended up using a 10" wide 255/60R15 that looks just right with steel wheels on this NASCAR legend. 

That’s all for now. Next installment will focus on tire diameter.

Comments on Whats the biggest tire that will fit?

Sunday, November 8, 2009 by Ken Gutierrez:
I own a 2004 Toyota Sequioa. My stock tire size is 16x 265/70R. Whats the Widest size tire I can install on my stock rims?
Sunday, February 7, 2010 by Joe:
I have a 2010 Cadillac SRX with 20"x 8" rims and Michelin P235/55/20 tires on it. I don't like the low profile type tire, because is not a comfortable ride. I would like to maybe put a tire on it that has more rubber side wall to make the ride more smooth and not so rough, is this possible with a michelin tire or at all without scrubbing any fenders or other parts? Thank you for any help.
Monday, March 22, 2010 by franklin.t:
i want to know how or if i can fit 22' rims and tires on my pontiac g6 2008....and if you could tell me the size tire or how i can find more info.....
Sunday, May 16, 2010 by Blake Caldwell:
Hey i have a 2009 mustang that ive blacked out and i was wondering which low profile tires to get that would fit the 20" rims i have.
Tuesday, July 6, 2010 by Craig Rogers:
I own a 2008 Toyota Tundra CrewMax 4x4 and I am looking at buying a new set of AT Tires. I would like to know what is the biggest tire that I could install with out any rubbing during turns and without installing a lift kit. Thanks
Sunday, August 21, 2011 by Chris B:
I have a 1998 Chevy c 1500 stock height and i am wanting to put A/T tires on.What is the biggest tire i can install with out lifting the front?
Friday, December 23, 2011 by Charles W:
I have a 2000 buick lesabre.I have P21570R15 oon the car now. Will P21565R15 fit and not have any issues on rubbing during turns?
Friday, August 3, 2012 by Angel:
Working on 1997 Chevy Tahoe, what is the biggest tire I can put on vehicle without lifting the vehicle?
Wednesday, September 12, 2012 by Rick:
will 235x55x17 tires fit my 2006 magnum with stock wheels?
Tuesday, December 11, 2012 by Mark Theobald:
will 225/60ZR16 Kumho Ecsta LX fit my 2004 Mitsi Galant ES?
Tuesday, July 9, 2013 by ricky ball:
what is the biggest size wheel I can fit on 1966 Plymouth belvedere II
Monday, July 15, 2013 by Ethan:
As I have shown above it is necessary for you to measure your own car as we dont have some of these classic cars in our database.
Friday, August 9, 2013 by Senaid Mujagic:
245/35/r20 5x114.3, will those size rims fit on a 2010 ford fusion sel?
Friday, August 9, 2013 by Ethan:
No, the 245/35R20 is a bit too tall for your Focus.
Saturday, January 11, 2014 by derek:
I have 2012 f150 super crew with 265/70/17 stock tires,could you fit 285/75/17 or what is the max size you can do
Tuesday, January 14, 2014 by Ethan:
According to our website the 265/70R17 is the only 17" tire that will work without a suspension lift.

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