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I've got a Solaris Max which is built up with Hunt XC wide wheels and has a WTB Trail Boss 2.4 on the rear.
When I'm riding I can feel the tyre squirming like it's flat. When I put a bit more pressure in it feels very harsh and doesn't seem to grip well.
Would the relatively narrow inner width of the rim (25mm) be part of the reason it feels like this? Would there be any benefit in getting wider rims?
What sort of pressure are we talking?
2.4" is a bit wide for a 25mm rim, but then BITD we all ran 2.1" tyres on 17mm rims and no one died.
It could be the tyre, either the shape or the carcass could influence it. The rim width could also make a difference.
I run an ARD insert in the back of my hardtail as i feel it gives a better middle ground between squirm and bounce at lower pressures.
This may not help you as I'm running 29mm ID rims with either 2.3" or 2.6" tyres.
Pressure wise I'm finding 22psi squirms then once km at 25psi it seems to lose grip.
Obviously I tried running between these pressures but it doesn't seem to make any difference!
Is it a Tough or a Light carcass tyre? 2.4 on a 25mm rim is a hair narrow, but not massively so. I’d imagine a light carcass tyre to be quite unsupportive on the back if you’re at all abusive with it though.
When I’m riding I can feel the tyre squirming like it’s flat. When I put a bit more pressure in it feels very harsh and doesn’t seem to grip well.
That sums up my entire experience of plus size tyres.
Also I'm pretty sure we used to run 2.4/5 DH tyres on 19/21mm rims without thinking about it. Tougher sidewalls do help.
Assuming the pump is accurate, you're very close to the minimum inflation pressure for the WTB tyre. and that minimum inflation pressure is for a 70kg rider. For every 5kg, they recommend and additional 2-3psi.
How much do you and your gear weight?
Yes a wider rim will reduce squirming given the same pressure
22 psi is pretty low.
For reference I'm 85kg and use a 2.3" DHR II on a 30mm Hunt rim. I typically go for 27psi on the rear.
Rider and kit is probably 95kg or just under.
I think it's the light carcass tyre so that could be something to do with it was well.
That’ll be it then.
Trail bosses are not really a “grippy” tyre. They’re nicely fast on hardpack and fun/drifty in dry corners, but they’re bloody useless if it’s all soft.
I’m over 30kg lighter than you, and when I was using a 2.4 TB Tough over the summer on a 30mm rim was at more like 27psi.
2.4″ is a bit wide for a 25mm rim
I'd say it was close to optimal.
The issue is the light carcass and the hard compound IMO. Your pressures are fine.
I have the same here on 27.5" HT with just about any tyre on, apart from Continental due to their rigid sidewalls.
Too low and I can feel them squirm and fold in any good corner, too firm and you really do feel the lack of grip in places...
I would also agree about rim width not making that much difference, I run 2.5" tyres on 21mm rims and don't have issues. It never used to be an issue when rims didn't come any wider.
Yeah I think you have your answer here - nothing wrong as such with your setup, but it probably isn't right for you.
Nothing wrong with benefitting from tougher kit! I'm up to about 85kgs in kit on a hardtail and also can't get away with things lighter folk would. Supergravity tyre on the rear for me, plus a ProCore insert. With that I can ride around 24psi on the rear without squirming or damage (35mm ID rims, but that isn't as vital to me as the tyre and insert). 22psi in a light weight tyre would be a puncture and burp-fest for me - yep I've tried 🙂
Always helpful to remember that you're riding a mountain bike, not an F1 car...