We test WTB's high volume cyclocross tyres on and off road
WTB’s Cross Boss tyre is a nominal 35mm width cyclocross tyre. But its main feature is a very high side wall, so that there’s a lot of air volume in the tyre. It’s also tubeless ready and I was able to seat it quickly and get a tight seal on WTB’s own Asym rims using a reservoir pump (although not with a standard track pump).
The big advantage of the high sidewalls for mixed terrain riding on rocky off road is that the Cross Boss can be run at low pressures to help with grip and bumps. I ran the tyres down to around 30psi tubelsss without any problems with bottoming out on uneven surfaces or burping. They do get a bit sloppy on climbs and tarmac at 30psi though and I’ve normally run around 40psi.
With such a high profile, clearance may be an issue with some cyclocross frames and I got some scuffing of the chainstays when using the Cross Boss tyres in more muddy conditions.
Watch: How to set the perfect tyre pressure
The tread pattern consists of quite closely spaced knobs, without sipes. These grip well in both dry and damp conditions. They are a bit prone to clogging in mud, although this soon clears. They also roll well on tarmac, allowing a good speed to be kept up.
The sidewalls are not super-thick either. I may have been unlucky, but I had two cases of flints cutting through them. They are also slightly prone to sweat sealant, although this did not result in significant loss of pressure between rides.
The Cross Boss is a great tyre for mixed condition riding, with its high sidewalls meaning that it can be run at low pressures for additional bump smoothing and grip. But the close tread pattern does result in some clogging in more muddy conditions. Clearance and sidewall damage may be issues too.