With the R4 320s, Bontrager have basically made an open version of their high-end R4 tubulars, using the same compound and width as well as keeping those very pro-looking tan sidewalls. Don’t confuse these with the already existing R4 Road or R4 Aero, they’re different tyres that have been around for a while now. With the 320s, Bontrager have also removed the quandary as to what width tyres you should ride as here there’s only one choice: if you want a set you’re getting 25mm, because that’s all there is. Seeing as 25mm has all but become the standard for road tyres, that limited choice isn’t the end of the world.
Casing is a premium 320 tpi (threads per inch) which means they’re supple and flexible, but the trade-off is that as a result they won’t be as tough and resistant to punctures. The R4s have Bontrager’s Hard Case Lite puncture protection underneath the tread, but as you’d expect from a tyre designed for racing, it’s more of a cursory nod to staving off road shrapnel rather than a concerted attempt to prevent anything from piercing the exterior. Don’t get me wrong, I’m not saying you’ll be stopping every few miles to stick another patch on your inner tube, but if you commute through a city don’t be tempted to stick these on because those little bits of road detritus that your usual hard-wearing tyres see off with no trouble may well have you stopped by the side of the road swearing when you’re riding these.
I had one puncture during testing, and it was a nasty tear right through the tread in the middle of the back wheel. I couldn’t find the culprit when I stopped to repair the tube, but given the size of the tear whatever caused it must have been pretty sharp indeed. But although my regular test route includes some pretty shoddy roads and a few paths that barely qualify as ‘roads’, that was the single puncture I suffered during testing.
The ride quality of a tyre like this is what really matters. They’re designed for racing (or, if you don’t race, as a Sunday best tyre), not necessarily all-out durability, and on the performance front these really shine. Perhaps the biggest compliment is just how confidence inspiring the grip is. The best tyres are marked out by the way they leave no doubts in your mind as you head into a corner at high speed and these are right up there in that regard. There’s a definite sureness about the way they hold the road even if you’re leaning hard into a corner, and that breeds the confidence to keep pushing hard. On top of that, and purely subjectively of course, they roll very well and tick along very nicely indeed, although I have no way of empirically testing that out. Still, a fast and grippy tyre is a good thing indeed, and the suppleness and 25mm width lends itself to comfort.
Weight-wise, their 226g is pretty good for a set of 25mm tyres, and they’re easy to fit although that obviously depends on the rim (you scoff, but even subtle variations can make fitting certain tyres a nightmare). I fitted these onto three different sets of wheels to check, and although they were pretty tight, they didn’t verge into the territory of being full on frustrating.
The Bontrager R4 320 tyres are made for going quickly, not for all-weather durability. If you commute on them (which would be madness at £55 each) or want them to regularly ride on roads littered with debris, then you’re probably barking up the wrong tree, but save them for races or slip them on for fast rides, you’ll be rewarded with a very capable set of tyres that have grip in abundance and make cornering a joy.
– Fast, soft compound which provides excellent grip
– Easy to fit
– Puncture protection is low
– Only available in one size