I used to have a set of Stan’s arch EX wheels that had an internal of 21 mm and I had maxxis ardents set up tubeless 650b x 2.4. Rode these for several years as low as 7 psi on deep Colorado snow and never had a problem. On another bike currently I have Stan’s Grail ZTR rims with an internal width of 20.3 mm (a whopping .7 mm difference!). These rims are rated for a max width tire of 42 I believe. For the last couple years I have been running 700x43 tires with no issues whatsoever. I have always been interested in running bigger tires on this bike like a 1.9-2.0. Why is it one rim that was .7mm wider worked well for a 2.4 but the grail rim recommends a max tire width so small? I can’t see where .7mm would make one lick of difference.
Wheel width vs max tire width
iowamtb
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I used to have a set of Stan’s arch EX wheels that had an internal of 21 mm and I had maxxis ardents set up tubeless 650b x 2.4. Rode these for several years as low as 7 psi on deep Colorado snow and never had a problem. On another bike currently I have Stan’s Grail ZTR rims with an internal width of 20.3 mm (a whopping .7 mm difference!). These rims are rated for a max width tire of 42 I believe. For the last couple years I have been running 700x43 tires with no issues whatsoever. I have always been interested in running bigger tires on this bike like a 1.9-2.0. Why is it one rim that was .7mm wider worked well for a 2.4 but the grail rim recommends a max tire width so small? I can’t see where .7mm would make one lick of difference.
It may be less about the actual tire and rim combinations and more about who is making the recommendations. There are lots of general guidelines printed and I think you are at the outside edges or completely outside of many of them with the 2.4 on a 21mm. Lots of folks do this and find the performance to be fine.
The 1.9 or 2 on a 20 mm that you are considering is right in many of the recommended ranges though, so unless there is something particular about those rims, it seems odd that they recommend max 1.65 inch tire. Are those MTB rims?
The 1.9 or 2 on a 20 mm that you are considering is right in many of the recommended ranges though, so unless there is something particular about those rims, it seems odd that they recommend max 1.65 inch tire. Are those MTB rims?
The grails are cross rims.
Could be.
If you want a manufacturer-neutral guideline. See the ETRTO specification-- the latest update one in 2022, not the outdated spec.
20mm internal width and 21mm internal width both support tire as narrow as 25mm.
But the maximum size vary as shown in the image.
21mm internal width support 2.1" (53mm) unconditionally.
20mm internal width somewhat support 2.1" (53mm) with an asterisk*.
![Image]()
20mm internal width and 21mm internal width both support tire as narrow as 25mm.
But the maximum size vary as shown in the image.
21mm internal width support 2.1" (53mm) unconditionally.
20mm internal width somewhat support 2.1" (53mm) with an asterisk*.
That’s crazy lol. Hard to believe 1 mm, or in my case .7 mm, can be a game changer. I was just reading an article where a shop built a Soma Wolverine, same bike as mine, using Pacenti SL 23 rims with 29x 2.1 tires and had nothing but great things to say about the way that bike handled and rode. I looked up the SL23 rim and it’s internal is 18. 😬
Personally, I never deal with tire rim combo where maximum tire size is a concern.
I hover more on the opposite end where the tire is just wide enough for the rim.
Like 28mm tire on 25mm IW rim.
And 2.2" tire (56mm) on 29.9mm IW rim.
So, I can't tell you how it'd perform.
I hover more on the opposite end where the tire is just wide enough for the rim.
Like 28mm tire on 25mm IW rim.
And 2.2" tire (56mm) on 29.9mm IW rim.
So, I can't tell you how it'd perform.
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Back in the good old days of 26", I always ran "wide" tires on my Mavic XC717 rims. Those were 559x17 and printed right on the rim was max tire width 2.3", which is ~58mm. I never quite got 2.3" of width out of my tires because the rim was so narrow, but I didn't have any problems, either.
I think the philosophy on tire/rim combinations has evolved a lot in 15 years, the fact that you are reading the specs for CX-specific rims probably plays into it, and each manufacturer has their own ideas about what works well.
![Image]()
I think the philosophy on tire/rim combinations has evolved a lot in 15 years, the fact that you are reading the specs for CX-specific rims probably plays into it, and each manufacturer has their own ideas about what works well.
I managed to get ahold of Stan’s tech support and asked them this question. The guy said it would work. It may not be ideal but he told me he has been known to run these grail rims on a mountain bike before. He let out a chuckle and said wasn’t the best application but it worked. If I go wider it will probably be 1.9-2.0. No wider than that.
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