Is there an ideal tire-width-to-rim-width ratio?

Maybe the title isn’t quite accurate, I’m not sure. And at face value, I’d be mixing units (in and mm), so lets not think too much into ratios here.

I’ll explain more. I am building a carbon wheel that is 33 mm wide (AM933 from Light Bicycle). I’m searching for a tire. Now, sometimes the same size tire has a choice of widths. For example, the MAXXIS Rekon has a choice of 29x2.4 and 29x2.6.

Considering my 33 mm wide rim, which would be the best choice? Is this something that can be answered without trying both? In other words, because there isn’t much of a difference between 2.4 and 2.6, would it simply depend from one tire model to another?

And when I say best choice, I guess I am referring to trying to eliminate the tire doing things I don’t want it to be doing (i.e. making the profile too square or something, etc.).

Or maybe someone has a chart. Just figured I’d ask haha. Thanks for reading, and thanks for any insight,

Its late here so I don’t have time for a long answer… but here is a chart to start the discussion (while I sleep)

Source: Tire & Rim Fit Chart – WTB


BAM. I knew someone would have a chart. Thank youuuuuuuu!

I was wondering something along the same lines thanks for asking. In my case I have my Nimbus Oracle 27.5 with a Duro Crux 3.25 Tire and 42 mm rim, which I have no complaints about except that the tire rubs against the frame.
I was wondering if dropping to a 3.0 Tire would be enough to stop the rubbing or if I would be a better off with a 2.8. It seems like it’s somewhat difficult to find much selection of 27.5 x 3.0 tires.
( it’s also surprising how terrible search works when trying to find 27.5 X 3.0 tires on Amazon and most other places!)
I’ve seen people say good things about the Surly dirt wizard, which I have found in 3.0 as well as a lot of people seem to have positive things to say about the Nobby Nic which I’ve only found in 2.8 which I wasn’t sure how well that would work with a 42 mm rim.
Was leaning towards a 3.0 but hopefully it provides enough extra clearance to completely stop the tire rubbing against the frame…

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Thats the stock tire for that cycle right? I’m certain it is. Sounds like you may have an issue with dishing with that wheel. It shouldn’t rub.

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Yes all stock. There is very little clearance between the tire and frame, like 2 mm or so on each side. Somewhere around here I’ve got a picture of it…
The oracles used to come with a 3.0 tire from what I hear, I wasn’t sure if they widened the frame more to accommodate the switch to 3.25 tires and or if maybe I got an older frame or something.

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Yeah, I have the green Nimbus MUni version of that 27.5, so I’m familiar. I’ve had to dish that wheel at one point.

Share some photos. Might be able to help.

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I posted some pictures here where we were talking about frame Flex:

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Huh. And it never got solved? I need to go look at mine with the Crux. I know it was tight-ish, but I never had any issues.

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I was wondering since the steel one is newer if they made the frame wider there or if it just flexes less because of it being Steel but yeah I’ve more or less just been living with the annoyance planning to someday buy a smaller Tire

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Be aware those charts don’t give a perfect answer to how to eliminate things you don’t want your tire to do. It may help you, but you’ll definitely have to try it out to be sure. E.g., I have a 32mm rim (EN732 from LightBicycle) that I use with a 3" tire. That works perfectly, the tire behave as I want it to behave while it is not recommended by this chart.

As a matter of rule, I’d usually go for a narrow rim/wide tire combination to avoid the square-tire effect. The 2.6" Rekon may be better in that case.
BTW, that’s a great tire I use on my fixed 27.5" for DH :slight_smile:

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Yeah, what you say makes sense. That chart is a great start, but isn’t the end-all-be-all. I wanted to try a Schwalbe, but I agree that the 2.6 Rekon may be my best bet.

Thank you!

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Here is the rest of the chart with the legend:


Sweet. Thank youuuuu.

According to UDC when I called via phone, the 27.5 frame was widened when they switched from the Kenda Havok 3.0 to the Duro Crux 3.25. The gaps on my frame measure 6mm on the right and 4mm on the left.


While waiting for the hub to arrive, I’ve ordered: Maxxis Hookworm (29x2.5) = 63.5mm width. Jones C-Rim (29x56) = 49mm inner width. This puts me right into the “not recommended” range. I’ve mounted the tire on the unlaced rim, and it has the right “look”.

I’d be curious to get your review once the wheel is built. I have tried a KH Freeride rim (50mm inside I think) with a Maxxis Grifter 2.5" tire and that was lame. The tire was square and it was horrible when trying to turn. I hope yours will behave better.

I believe with a round tire that is usually run at higher pressure like the hookworm, you can get away with being outside the range more than on a low pressure MTB tire with a square profile.

Especially since it’s a BMX(-ish) tire, with tread pretty much all around.

that is correct. The bike industry seems to be going back to narrower tires again. eg. at Schwalbe there are max. 27.5x2.80 and 29x2.60 - yes, you heard that right, there is no larger than 2.6 with 29". The same applies to Continental and Michelin. I don’t know how it looks with Maxxis and Kenda, but 3 inches seems to have had its day.

Duro is probably an exception. The 3.25 size is special. Unicycle forks with 100mm bearing spacing are actually not made for these dimensions. But it works with construction tricks.

Wide tires on narrow rims cannot be ridden with such low air pressure. Example ?
According to the information, the Surly Nate 26x 3.80 could be ridden at 0.4 bar - on a fat bike rim. I only have a 45mm rim on my Fattys. The tire rides with it without any problems, but the air pressure limit is 0.7 bar, exactly the same as when I mount a 3" tire.

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Can you tell by appearance if this setup is overly “square”. Inflation is ~.7 bar / 10PSI