# Fundamental (okay, stupid) tire questions

Discussion in 'The Garage' started by ArrowheadK5, Mar 25, 2002.

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1. How are tires measured and what do the numbers in tires' names mean?

2. How does the width of the wheels/rims affect the width of the tire that can fit?

3. Did any Chev trucks come with 8-lug rally wheels?

Thanks; This is really just an easy way for me to learn simple things w/o actually doing any kind of research.

2. ### Mudstud1/2 ton status

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1. The tire size thing is kinda wetawded. It's something like the first number in the size is the footprint width in centimeters. The second number in the size refers to the side wall hieght (from floor to bottom of rim) and is the percentage of the width of the footprint. The third number is the rim diameter.

This is the way I remember it being explained to me. The floor is still open.

2. All I can tell you is that if you run a wide track tire (14.5) on a..., say 8" wheel you are gonna have a huge driveability problem.The wheel will move in and out of the tire latterely going down the road which creates that floating, unstable feeling. The opposite set up is dangerious and stupid from a 4x4 standpoint. Who'd want their wheel wider then the tire? If you do run a super wide tire on a narrow rim and you break the bead it is more difficult to reseat the bead then if you were running a wider wheel. I think I said that last part right!!

3. I don't know for sure about 8 lug rally wheels but my guess is yes, they made them.

There, now your lazy butt can read this and learn "w/o actually doing any kind of research".

3. ### Hossbaby503/4 ton status

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Ok, on standard tires. This is my tire size.
32x11.5x15

32 = diameter of tire (supposedly)
11.5 = width
15 = rim size

All numbers are what is claimed by the factory. Most tires don't actually measure true height. If you are asking about metric tires I have no clue. It was explained to me once, but I don't remember.

4. ### 87GMC1/2 ton status

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metric tires are in centimeters
example 205/45r16
205 is the "section width",means the tread is 205 centimeters wide
45 is the "aspect ratio"and is a percentage, means the sidewall height is 45% of the section width
the last number is the well diameter

5. ### Chris Demartini1/2 ton status

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<font color=blue>Section width is the widest point of the tire, usually halfway up the sidewall. My swampers have a 12.5" section width, but a 10.5" tread width. Metric sizing is not difficult. For example, a 305/75/16 has a 305 CM section width (widest point on the tire, not tread width) the sidewall height is 75% of the section width, and it fits on a 16" rim. I don't have it off hand, but the metric to flotation (inches) formula has been in the mags a few times

6. ### 87GMC1/2 ton status

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one inch=2.54 centimeters

7. ### aksidentproan1/2 ton status

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Actually, metric tires are in Milimeters. 205=205 milimeters or 20.5 centimeters.

Evan

8. ### 74k5inVA1/2 ton status

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Since we are all learning about tires, can someone explain backspacing, how to measure, and how do you know how much you need, etc, etc,

9. ### 87GMC1/2 ton status

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Backspacing is the measurement from the whel mounting srface to the inside edge of the wheel. To measure, lay a straightedge across the wheel and measure down to the wheel mounting surface. As far as how much you need, I would post what you set-up and what you tires you are trying to fit and maybe someone can tell you what worked for them.

10. ### 74k5inVA1/2 ton status

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thanks, but how can you adjust it?

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