Tire Size

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Jul 17, 2015 | 06:47 AM

gmhill33

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Tire Size

Greetings,

How much taller and wider are the 31×10.5's than a stock tire?

Thanks,
Gary

Jul 17, 2015 | 11:30 AM

mg94mg94

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235-75R15 is about 29" tall and 9-1/4" wide. Thats without measuring though.

Jul 17, 2015 | 12:17 PM

gmhill33

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So you gain a couple inches in height by switching to the 31's. Those can be put on the stock rim?

Thanks,
Hardy

Jul 17, 2015 | 12:19 PM

mg94mg94

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IIRC, people use them on the stock wheels, but they rub a little on tight turns.

Jul 17, 2015 | 12:23 PM

Nothing Special

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From: Roseville, MN

General rule of thumb is that the rim width should be about 2" less than the tire section width. So a 10.5" wide tire should be on a rim that's 1.25" wider than the rim for a 9.25" wide tire.

However, that general rule of thumb isn't a hard and fast rule. you can put that tire on the stock rim. It MIGHT wear faster in the center, and it MIGHT not handle as good as it should. But you might not notice anything either. A lot of people do go even wider than 10.5" on stock rims.

Jul 17, 2015 | 01:52 PM

mg94mg94

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According to the book at work, the safe rim sizes for a 31x10.50r15 are any J type from 7-9"

Jul 17, 2015 | 02:09 PM

gmhill33

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Thanks everyone for the replies.

My questions now are. What is the proper size rim for the tire and is there anyway to make it not rub?

If you haven't figured it out by now, this is my first truck.

Thanks,
Gary

EDIT: One more question. To measurer the size of the tire, do you measurer around the tire or the height from the ground to the top of the tire?

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Jul 17, 2015 | 03:45 PM

gmhill33

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Quote:

Originally Posted by GocartMozart

I am running 31x10.50R15 on stock 15 x 7.5 inch steel rims. No rubbing whatsoever. They handle great all around. 1995 F150 4x4. Might handle a little different for RWD though.

Thanks for replying. Mine is 1995 f150xlt Flaseside 2wd.

Thanks,
Gary

Jul 17, 2015 | 05:26 PM

#10

mg94mg94

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Quote:

Originally Posted by gmhill33

One more question. To measurer the size of the tire, do you measurer around the tire or the height from the ground to the top of the tire?

31 - 31" tall
10.50" wide
15" rim

Now here is where it gets interesting. For 235-75R15

235 is the tread "section width" in mm
75 is the aspect ratio, meaning the sidewall is 75% of the section width tall.
15 is the rim diameter.

So to get the total height, you have to do:
(235x0.75x2)/25.4 +15

The 2 is for 2 sidewalls and the 25.4 is to convert mm to inches.

Jul 17, 2015 | 05:37 PM

#11

gmhill33

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Quote:

Originally Posted by mg94mg94

The only thing that comes to mind is "WOW"! Thanks for the break down. I would have never figured that was how you got the height of your tire. So the 31" are considerably taller than the stock tire. That makes me want to get them even more.

I have another question (maybe I should start another thread). I have looked online for a leveling kit for my truck and it seems that it is only two springs. Is there anywhere that I can find the height of the springs? I have a brand new spring that i am going to put on the passenger side and would like to know the difference. The guy I bought the truck from bought two front springs but only one spring tower so I'm going to get the other spring tower to level the truck with the drivers side.

Thanks again for everyone that has replied.

Gary