I apologize in advance. I know this topic has been talked to death, but I still haven’t been able to find a concise answer. Most people are wondering how fat of a tire they can get by with on a particular rim, but I’m thinking in the other direction. I’m wondering how skinny of a tire I can put on my rim. From the UDC website, it’s a “Nimbus Dominator 2, 24” (black) 36H, 42mm wide, aluminum doublewall, reinforced eyelets, ERD 492". This is just the stock rim that came with my 24" Nimbus muni I bought new last year.
I’ve looked at Sheldon Brown’s website, searched this forum, and a couple of mountain bike forums, and I think I have a general idea, but what I’ve come up with is that I shouldn’t use something skinnier than a 2.4" tire. I used 42mm as my rim width and Sheldon’s formula:
“A general guideline is that the tire width should be between 1.45/2.0 x the inner rim width.”
I know this is just a general guideline, but I’m wondering if other factors might allow me to go skinnier on this particular rim. Right now I’m mostly curious to see how skinny I can go, but eventually I’d love to figure out what my range of tire widths are for this Dominator II rim.
Thanks, and sorry for another annoying tire thread!
If you aren’t running it off-road I would be comfortable going as skinny as the outer dimension of the rim. 42mm = 1.65"
Having the rim as wide as the tire increases the chance of pinch flats and rim damage if riding on rocks or other hard uneven surfaces but will give you really good stability right down to rim-strike pressures. It can be nice in winter when risk of pinch flat is reduced.
Oh that’s an active conversation I’m having… about wide tire on skinny rim.
But there’s info out there that’s useful both ways!
The other problem with a skinny tire on a wide rim, is that the sides are more vertical than the manufacturer planned. Which changes the dynamics of the tire, especially when turning - which is where it concerns us, unicyclists…
Notube has a neat visual explanation on their website: