I thought I understood tire and rim size designations but maybe not. I have seen posts saying the 2nd number is the rim size, others say it's the 3rd.

One Y2Kodiak owner says his manual says front rims are 6.0 and rear are 7.5. Yet original tire sizes for this machine are 25x8x12 and 25x10x12.

Can someone clear up the mystery of how tire and rim sizes are designated (hopefully there is a standard!) at least to the point where I can determine which optional tires might replace those listed as originals in the sales brouchures?

 

Ok, the 3rd number is the rim size, your friend looked at the with of his rims not the diameter. If his stock tires are 25X8-12 and 25X10-12 then he has 12'' diameter rims. That means that if he wanted bigger tires he could get them and in any width, as long as the 3rd number was 12. He could put 27X12-12 vampires all round if he wanted. They would fit his rims, just keep the 3rd number the same. He has 12X6.5 and 12X7 rims or whatever nubers you gave.

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Matt Sibley

1999 Honda 300 4x4 Vampires, Lift Kit, 2500lb WARN winch

 

Thanks Matt. The 3rd number being the rim size is as I also understood. However, I am wondering about your statement "That means that if he wanted bigger tires he could get them and in any width, as long as the 3rd number was 12."

Are you saying you could replace a 25x8x12 with a 25x12x12 or vice versa? Seems like tire width would be a factor in its ability to stay on the narrower/wider rim.

 

It all depends on the width of the rim.
Put simply:

25 x 8 - 12 This means

Tire is 25" tall, 8" wide, and fits on a 12" tall rim. Tall meaning diameter.
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Now. The width is a factor as well. Rim sizes look like this:

12 x 6.5" or maybe 11x8"

Rim sizes would be 12" diameter and 6.5" wide for the first, and say 11" diameter and 8" wide for the second one that I just showed.

The 6.5" wide rim would not be wide enough probably for a 12" wide tire. You would need at least a 12x7 or even a 12x8 for that wide of a tire.

If you had the 11x8" rim, then you could mount a 12" wide tire on it, but when you bought the tires, you would have to make sure it was a tire for an 11" diameter rim. Say, a tire that measured 25 x 12 - 11.

In atv tire sizes, the last number is always going to be the wheel diameter or height. The width of the tire is the middle number and the tire height is the first. The thing that you have to keep in mind is whether or not your wheels are wide enough to support a wider tire.

I have 12x6.5" wheels all the way around on my AC500. I have 26x10.5 -12 tires on it. That is about all I can get on there without getting a wider rim. If my back wheels were 12x8, then I could mount say a 27x10-12 tire on the front and a 27x12-12 tire on back.

If you have read all of this crap, then you should have tire sizes pretty much stamped into your brain by now.


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Andy Bassham *(1999 Arctic Cat 500 4x4, 1989 Honda 300)*

 

Andy, I GOT IT..I GOT IT..I THINK I GOT IT! Rim diameter is cemented in. Now only question left is whether there are specific guidelines as to which width tires will fit on which width rims. Is there some reference, for instance, that says a 6.5" rim is designed to accept 8-10 inch wide tires and nothing more or less?

What I'd like to be able to do is KNOW which size tires will properly fit a specific rim without having to rely on a salesman who may be very competent at selling.

 

I just ordered a bigfoot kit for my SP500. The rims were 7" wide & 12" tall. The tires were 27x9.75x12 front and 27x12x12 rear. They say that unless you want to pay the extra mega bucks for 12" wide rear rims that 7"-8" is standard (mostly 7"). The only other factors are how many cc your machine is, and how much clearance you have(ie. fenders and shocks or struts, and what you plan on doing. We have found for trail riding with some mudding that a narrower tire 10" in the front really helps. If you plan on driving straight to the mud pits then you could easily use the 12" wide tires in the front if they would fit, but they trail ride poorly.

 

I wish I has some better reference on wheel width as well. The largest 4x4 rim at least in 12" diam. that I have seen from ITP is 8" wide (maybe 8.5 for some special offset or something) and not many places even carry those. I suppose most people mount 12" wide tires on 7" aftermarket wheels. Even though its only a half inch, I was told by a few places that it wouldn't be a good idea to mount 12" tires on my 6.5" stock rims. Mainly for the ballooning effect that it causes. My 10.5" wide tires balloon out pretty good as it is. Not so much that the tire is not stable on the wheel, but enough to keep me from dinging up the sides of my wheels. I could get the 12" tires to mount up, but they would balloon out over the side of the rims something awful.

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Andy Bassham *(1999 Arctic Cat 500 4x4, 1989 Honda 300)*

 

My Tri claws 27x12x12 came mounted on 7x12 rims. They dont balloon out very bad at all. My friends 27X12X12 Vampires are about the same, and they are mounted on factory 7x12 rims also (500 magnum)

 

I have 27x12x12 Vamps mounted on some ITP 12x7 rims and they look pretty good.

The widest aftermarket wheel I have seen for 4x4's is the Douglas aluminum rear which comes in 8 in. widths.

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http://users.nlamerica.com/dixiebai/atv/

 

Thanks for all the responses to my question. Seeing no responses stating specific limits to tire width vs rim width, I called a couple tire manufacturers' consumer information numbers. Both essentially said that there are no published industry standard width limitations. Each had specific tires which they remommended depending on rim size. One listed maximum width and maximum height tires based on a 6 inch rim, but had different limits depending on which of their tire models you were buying, even though the rim size stayed the same.

So I guess the bottom line is that there is no way to determine recommended tire widths for a specific rim other than to contact the manufacturers' literature and hope they publish tire/rim size recommendations.