# Tire size question

Discussion in 'The Garage' started by chevyracing, Nov 24, 2003.

1. ### chevyracing1/2 ton status

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What is the metric equivilant size of a 31X10.5X15 tire please?

John

2. ### 4GUNZ4X4Z1/2 ton status

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78.74cm X 26.67cm X 38.1cm =

787.4mm X 266.7mm X 381mm =

31" X 10.5" X 15"

3. ### Hossbaby503/4 ton status

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My dad runs 265x75x16's (or something real similar) on his F350 and they measure 31" tall or so but I don't know the width.

4. ### reeser1/2 ton status

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the metric equivalent to a 31x10.5 is a 245/75/16. yes the 265's measure a true 31" but a 31x10.5 doesn't measure a true 31".

5. ### Chris_T1/2 ton status

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But that is a 16" rim.

The mathematical conversion is something like this:

Section width 10.5" x 25.4 mm/inch = 266.7 mm (265)

31 inch tire - 15 inch rim = 16 inches for two sidewalls

8 inches per sidewall x 25.4 mm/inch = 203.2 mm

203.2 mm / 266.7 mm = 0.76 (75 aspect ratio)

So the equivalent would be LT265/75R15 in a 15 inch tire (or a 30.6x10.4x15 if you want to split hairs)

245/75R16 mathematically is:

245mm / 25.4 mm/inch = 9.6"

245mm x .75 x 2 / 25.4 = 14.7 "

14.7" + 16" rim = 30.7" tire.

Giving you: a 30.7x9.6x16 (or 31x10.5x16 equivalent)

These get you close, but of course tire width and aspect ratios will vary with tire and load, etc, etc, etc. If rim size isn't a factor, either will work. You may be able to find more options in the 16" rim.

6. ### 4GUNZ4X4Z1/2 ton status

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Good lord... I didn't read that far into it. I was thinking more along the lines of a science project... doh. Chris T is on the money though.

7. ### chevyracing1/2 ton status

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So for my wife's Durango I need 265/75/15. Good enough, now I know what to ask for when I call around and don't gotta sound like a goober smoocher. Thanks Chris.

John

8. ### Hossbaby503/4 ton status

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If you are running a 15" rim then why don't you just run 31x10.5x15's?

9. ### thezentree3/4 ton status

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you sure the durango isnt a 16in wheel? two friends of mine have durangos, and they both have 16in wheels. theyre the swept 3-spoke jobbies. /forums/images/graemlins/wink.gif

10. ### 84_Chevy_K10Banned

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[ QUOTE ]
you sure the durango isnt a 16in wheel? two friends of mine have durangos, and they both have 16in wheels. theyre the swept 3-spoke jobbies. /forums/images/graemlins/wink.gif

[/ QUOTE ]

Many Durangos come with 31x10.50R15s

11. ### thezentree3/4 ton status

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i stand corrected /forums/images/graemlins/crazy.gif

12. ### Chris_T1/2 ton status

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You're welcome. I don't know if 265/75 is a common P-metric size or if they just call them 31x10.5. Maybe a little online searching for the types of tires you're looking for will tell. I'm pretty sure that one of sites with the 4x4 calculators has a conversion tool for floatation to P-metric sizes.

13. ### chevyracing1/2 ton status

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[ QUOTE ]
If you are running a 15" rim then why don't you just run 31x10.5x15's?

[/ QUOTE ]

Becuase we are looking more for a car tread tire than any kind of a truck tire. This is her work vehicle and it gets 30 miles of interstate to work and 30 miles home. I hate to go into a tire store and answer all of the questions they ask. I like to look around til I see the ones I want and say give me a set of those and leave with them. I mount and balance them myself. The ones I find that I like may not be offered in 31x10.5x15 but may be offered in the metric equivilent. How's that? /forums/images/graemlins/smile.gif

John

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