Lightweight performance clincher tyres with a cross-section greater than the benchmark 23mm are an increasingly common offering from the major road tyre manufacturers, with 25mm the “next size up” for most. The latest such from Continental is a 25mm version of the now-classic Grand Prix 4000S model, which superseded the plain old Grand Prix 4000 in 2007.
Just like its narrower sibling, the 25mm tyre has Conti’s Black Chili tread compound, a curvaceous tread pattern and a Vectran anti-puncture belt over its polyamide carcass. It is offered in folding bead format only and weighs a claimed 230g, 25g more than the 23mm version.
Fitment is as per the narrower tyre, meaning reasonably tight on most rims without being notably difficult to fit. Tested at the same 95/105 psi front/rear we use for 23mm rubber, the ride is firm yet supple and is notably more absorbent of road imperfections. Steering effort is not noticeably different and adhesion on bends is reassuring. Where the tyre performs less well is, inevitably, in acceleration, where the extra 50g per pair at the wheel circumference is keenly felt.
Then, too, there are fat alternatives in the Conti road range: both the GP Force and Grand Prix come in a 24mm section and use the Black Chili compound, the former weighing a scant 210g and featuring a Vectran belt at a small price premium. The latter weighs the same, saves £10 and substitutes a Poly-X-Breaker anti-puncture belt.
Expect the Grand Prix 4000S 25mm to be longer-lasting and more robust but slower than the Force and more puncture resistant than the Grand Prix but with little if any performance advantage. We’ll try some coast-down testing in the hope of nailing this one down.
Continental Grand Prix 4000S 25mm: £39.95