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With the trend of wider rims taking hold - white lightenings at 30mm int width and many Chinese rims of similar width, are the current tyres designed to be mounted on such wide rims?
Whilst I understand that the tyres will mount ok on 30mm rims, with some performance gains - less burping, less rolling resistance and so on, but are the current design of tyres performing at there maximum in this situation from a cornering perspective?
EG Hans Dampf 2.35 on a 23.5mm int width rim is going to pull the tyre in more making the side knobs protrude at a given angle.
When the same tyre is mounted on a 30mm rim the tyre is more bulbous so does the tyre actually loose some of its cornering potential rather than improve it even though the deflection is less?
Is it better to stick with a rim around the 23-25mm mark until until the tyres are redesigned around 30mm+ internal width rims?
It would be good if tyre manufacturers specified an optimal rim width for each tyre/size - looking at Schwalbe and Maxxis sites, nothing is mentioned at all.
I think asking the manufacturers for advice would be a fool's errand as they can't measure their own tyre widths accurately nor recommend sensible pressures!
But I think you're right that wider rims are not always a good thing for tyre performance. As you go wider you make the tyre more square which increases rolling resistance, tends to increase grip in looser corners but tends to decrease grip on hardpacked turns (look at the shape of a High Roller vs a Minion). A squarer tyre with more strongly supported knobs will tend to be more snappy on the limit too (same as with car tyres).
One of the Maxxis tyre designers posted a while back on mtbr commenting that he designed 2.3 high roller 2's around 23mm rims and 2.4 High Roller 2's around 25mm rims.
I think that the marginal increase of say 7mm internal width (23mm to 30mm), split across each side of a tyre, and then adulterated by the height of the tyre makes for only a limited change in tread profile, that is more noticeable on some tread designs than others.
I think what's much more noticeable is sidewall support at low pressure, and the increase in air volume it creates which allows even lower pressures to be run, feeding back as yet more grip and rolling speed.
sidewall support at even lower pressures? Hmmm... how's that work then?
oh, yeah... it doesn't
Quit looking for the holy grail in stupid "upgrades". ride your bikes a bit more and learn the limits of the tyres you actually have.
I'm running 2.75 dirt wizards on 30mm rims and they work well. The rims were fine with 2.3 spesh tyres as well though.
A wider rim can sometimes make a tyre more stable, which means that tyre pressures can be reduced
How much more stable? Reduce the pressures by how much? How much difference will it make? What happens as the tyre wears, will that reduce cornering potential (off-road)?
Choose a tyre that suits your local riding conditions, e.g. muddy, etc. and learn to ride it to get the best out of it. My tyres have always been better than me 😳
What made me question this is that a new AM bike came with 2.4 trail kings on 23mm int width rims. The TK's work ok but nothing special.
The profile reminded me of how my first generation Fat Alberts used to look on my 17mm/19mm rims where the grip was fantastic but they did look like they were only just staying on. I upgraded my my rims to 321 Mavic's but the cornering never felt as good. I started doing more DH. I dropped pressures but then the tyre seemed to be squirming like hell. I ended up changing to Michelin comp 24 up front and a comp 16 at the back, which never came up massive, but wow I could lean in the corners. They really opened my eyes to how a good tyre can grip when pushing hard.
Then it was onto the benchmark Maxxis 2.5 Minions FR and High Roller combo, which again are not massive but they do everything so well. When the Comp 32 came out I thought it was going to be game changer - that was massive with big burly tread, but I found it disappointing compared to its predecessors. That could come down to its weight also as it really slowed everything up whereas modern rubber is big but relatively light ~750/800g compared with 1.0/1.1kg. That said these 2.4 trail kings on my AM rig have come up over 1kg on the scales hence another reason why they are being dropped for a Hans Dampf/NN 2015 combo today. I do like the comfort that the big tyres give for AM/Trail riding but I am not convinced how good they are pushed in corners - maybe the HD/NN combo might educate me. Lets see - its another good reason to just go and ride.
2 rides on the HD and Nobby nic combo. So much better and fit the 23mm rims nicely. Volume wise at 2.35 they are tiny compared with the 2.4 Conti MK's.
The 2015 NN Pacestar on the back rolls incredibly well with much better cornering grip than the old NN. I could never understand why they were rated so highly.
Good read. Written in 2011 as well predicting 30-40mm by 2013. Certainly going that way with the carbon rims at that width..
It's far too complicated for me. The shape of the tyre isn't everything, it deforms depending on load, pressure etc. Ever since riding with a guy who had a car tyre on the back of his motorcycle I have decided the only way to know if something works is to try it. Shame trying out tyres is so damn expensive.
Good article.
I put a Minion DHR2 2.3 onto a Flow EX (25.5mm internal) rim last week. Really nice match - carcass and side knobs both measure 57.3mm wide at ~25psi. Fairly square but not so square it's slow rolling or unpredictable.