Tire to rim sizes

Patch164 · Feb 22, 2019

So in doing all my research to get new tires for my tractor I was told I can't or I'm not supposed to mount a 16.9 tire on a 13" wide rim which is understandable. However we bought a brand new 6310M John Deere in January and it has a 420 which converts to 16.9 on a wait for it 12" wide rim. So if it came from the factory that way can I put the 16.9 on my 13" rim? The size stamped on the wheel is 24Xw12L on the other tractor they are 30Xw13L does the bigger rim make a difference? My thought is if it's ok there it should be better on the 1" wider wheel.

SVcummins · Feb 22, 2019

I?ve got 480:80:38 tires on 14 inch rims 480 metric tires are a half inch wider than an 18.4.38 tires and they work fine so just under a 19 inch wide tire on a 14 inch rim

Brendon-KS · Feb 23, 2019

Different diameter tires with the same nominal section width can be designed for different rim sizes as shown by this chart. For the 420mm tires on a 24" rim like what your new Deere has the approved rim widths are 12, 13, and 14 inches. However, the approved rim widths for a 16.9-30 tire are 14 and 15 inches. There must be differences in how these different sized tires of the same general width are designed that makes them work best on very different rim widths.

(This chart is from the Titan Tire website but it is straight out of the Tire & Rim Association Handbook so the information is industry-standard and not brand-specific.)

Patch164 · Feb 23, 2019

What does the letter stand for behind the number? I see some are L and some are A. And the chart says you can put a 420 90 r30 on a 13" wheel or am I reading that wrong?

Brendon-KS · Feb 23, 2019

The various pre- and post-fix letters refer to subtle differences in the rim and bead geometry. Some are interchangeable while others are not.

You are reading it correctly that a 420/90-30 tire can "officially" go onto a 13" rim. However, the 16.9-30 calls for a 14 or 15" width. That's not to say that it wouldn't physically work on a 13" but the profile would be different than what the tire was designed for.

Leroy · Feb 23, 2019

The tire manufactures and the machinery manufactures don't think the same way Take the 2 trucks I had and on door post it called for a 215-75R-15 tire and tire manufactures said to use that tire only on a 6-7" wide rim. Now the truck maker only offered an 8" rim for those tires the tire maker said not to use on an 8' rim and it would invalidate the tire warenty. I ended up getting used wheels from an older model of my truck. I did put one of the recomended size on an 8" wheel for a spare and it did not look good. So who do you believe, the tire maker or the truck maker?

Patch164 · Feb 23, 2019

I would have to go with the tire manufacturer because they should know what their tires are capable of. But in reality I would go with whatever looks better to me. I think most of the time they put the recommended rim width so the tire wears more even and you get the most life out of it.

Leroy · Feb 24, 2019

Big thing for me was when you put correct size tire on acording to door post but then the factory only put a wider wheel on and if you bought new tires if you put it on the factory wheel the warenty on the tire was no good. Why would truck maker put on a rim that made tire warently worthless?

Patch164 · Feb 24, 2019

Well once they sell it they don't care about that. It becomes your problem then.

Tire to rim sizes

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