The Pirelli P Zero SmarTUBE RS swaps standard butyl for a TPU shell that weighs a fraction as much and rolls with less resistance underfoot. That lighter, thinner material is what lets a tubeless-ready setup run this tube and roll as fast as one filled with sealant, according to Pirelli's own testing, without the periodic top-offs or the mess when a valve clogs. It comes in three valve lengths, so deep aero rims and shallow climbing wheels both get a proper fit. Paired with the P Zero Race RS tire, we've found it holds that speed advantage through the kind of long, steady efforts where every watt actually counts. What Our Gearhead(R) Experts Are Saying:"I stopped checking sealant levels before long rides. The valve never gums up, so I just seat the tire and go."