What’s the biggest tyre I can run on standard 26″ rim?

I’ve built up a 26″ On One 465 Evo with a rigid On One fork for bike packing and XC and I absolutely love it. It’s fast and has taught me a lot of technique. Don’t worry, I’m not completely mental, I’ve also got a big bouncer!

I’m currently running a tubeless Hans Damf on the front and can run it as low as 18 PSI which gives a lot of give, but I’m keen to go bigger. Since there isn’t a arch on the fork, there is tons of clearance and the only restrictions are 26″ / 21mm Internal Diameter rim.

It would be quite costly to buy tyres and find they don’t work, so has anyone had any experience of running a bigger tyre?

Thank in advance.

We ran 2.5s happily on 21mm rims not so long ago though current fashion will tell you a 21mm rim is only good for road tyres.

I’d suggest see if you can get a knackered old fat tyre or something in the wanteds for postage or something and give it a go. If it inflates with a tube and fits, there’s your starting point, just decide if your worried about the tyre peeling on the rim. (Id think 2.8 is probably a sensible max personally, but it’s guess work in the first instance and even a correct size is nonsense since one manufacturers 3″ is another’s 2.5″).

(At 18psi though I’d find i was able to fit new wider rims a lot sooner than planned anyhow)

I ran a 2.4” Conti MK2 on a 19mm internal diameter Mavic. The profile was quite rounded but worked well I thought. Don’t think I’d have gone much bigger on it. That bike was 650b.

Current 650b is 25mm internal diameter with a 2.5wt Maxxis on it – much bigger and the tyre would be really rounded.

My 26er has a 25mm internal rim and the 2.4” on one chunky monkey is great on there. Possibly could go a little wider (although the fork crown on that bike would disagree).

Plenty of room in that fork for a whole bigger wheel, much better 27.5×2.8

unnamed1 by Shawn McFarlane[/url], on Flickr

Mavic say that an XM719 rim is ok up to a 2.7 tyre.

https://shop.mavic.com/en-int/xm-719-disc-j27300.html#1028=3283&1035=3504

Probably a good idea to check with the tyre manufacturer about what width rim they intend the tyres for, but a 2.5 inch tyre on a 21mm rim should be fine IME.

You could get a pacenti dl31 rim from planet x for £notmuch that’s 26mm internal

I find that 2.35s  (XR4 and Purgatory) are OK on my 819 and Flow 26″ rims as long as they’re pumped up firmish.  If run at low pressures they are prone to flip-flopping and burping.

Re: restless native

I love this, did you get the wheel custom made?

Hi,  Yeah velocity blunt rims on superstar hubs, 26 x 2.25 rear and 27.5 x 2.8 front.  If you are anywhere near the scottish borders you are welcome to try the front wheel.  This is the bike I use for bikepacking.