nicko, I don’t really know about the sidewall wear – I’ve had one of these XR4s on my lone MTB for a year and it was fine until recently* but most of my riding is in a very non-abrasive and unrocky area!
* Whilst going down something rather steep, droppy and chalky last month I got a 1″ slash through the carcass courtesy of a big pointy piece of flint. Put a tube in and continued and the tyre has since been patched so it can be used tubeless again – found a surprisingly large bit of flint inside the tyre which must have snapped off as it ripped open the carcass.
The problem with High Rollers (which the new ones address) is that you have to lean the bike enough to get full cornering grip – fine for a DH tyre because hopefully everyone who DHs can corner properly. Not so good for many XC and trail riders, including relative beginners like myself, hence my preference for a less ‘square’ tyre.
I’m curious to see how the XR4s perform at some rocky Welsh trail centres this weekend, as that’s the sort of thing they’re apparently designed for, although they actually work bizarrely well in Southern woodland singletrack in all seasons. I’ll then be doing a XC race with them on the following weekend!