The GP4000s’s are a staple amongst road cyclists, mainly due to the affordable price range, great puncture protection, and light weight. They are also rated as the best by tour magazine, though this magazine is renowned for preferring German brands anyway.
And on that note, this tyre is still made in Germany, unlike many other european brands, which have moved their manufacturing to Asia. The quality of the tyre is generally good, though I personally have had one tyre fail on me after about 500km.
First of all, the “black chilli” compound is a good compound, but it’s not great. The advantages are that it is rubber-based, not silicone, so it sticks to the road pretty well in the dry and doesn’t pick up every single piece of road debris. The disadvantages are that it wears pretty quickly, I only get about 2000km out of a tyre, and doesn’t grip too well on some surfaces when wet.
Secondly, the low resistance construction. They don’t provide a lot of information on this, but from seeing how the tyre is made, there is a layer of rubber on the outside, then a layer of silk (real or synthetic, I don’t know), then the breaker and finally the casing. This layer of silk, I think, spreads the amount of deformation to the outer layer of rubber, instead of deforming the entire tyre casing and all, which I think uses less energy, leading to lower resistance.
However, many feel that the tyre has a “dead” feeling. I think this is probably related to the construction, in that if only part of the tyre is deforming, there is possibly less absorption of road surface vibration, bumps, etc.
The tyre has a few other advantages not touted so much by the manufacturer.
Firstly, the puncture protection is excellent – I’ve had wear some tyres out on me without even bearing a puncture, and that’s with everyday commuting, training rides, and the occasional race.
The second is the light weight – they’re not the lightest, but at under 300g, with puncture protection, a good amount of rubber and so forth, it’s a lot of bang for your buck.
They also look pretty good, with the pseudo tread pattern along the sides and silver lettering. And they sound good, especially on a well sealed road they just hum along, they make a nice little ‘tssssss’ sound.
I’ve found that they don’t feel much different at 120psi then they do at 100psi, so just run them at 120psi or get a different tyre if you’re looking for something more comfortable, as noted above they do not soak up much of the road vibration.
This is a tyre that you could use for racing, training, and (given you can afford to replace them every 3 months or so) commuting. However, wet weather grip can be an issue, and the ride may not be as smooth cas some other tyres. But, for the weight and the price, you cannot do much better.