Downhill Mountain Bike Tires
Tires are what grip the surface of the ground and provide much-needed traction to a downhill mountain bike. Most commonly made of rubber, downhill mountain bike tires are usually two inches wide or wider, very thick so as to prevent puncture flats, and knobby and bumpy to provide as much grip as possible.
When purchasing a set of tires, downhill mountain bikers now have two options to choose from: tubeless tires, or tires with tubes. Tires with tubes are the standard style of tire - a tube, inflated with air, is cushioned between the downhill mountain bike rim and the downhill mountain bike tire. The psi, or pounds per square inch (pressure) of the tire can be adjusted through an air valve on the rim - lower pressures are better for downhill mountain biking, as the lower the pressure in the tire, the more traction and control the mountain biker can exert over the downhill mountain bike.
The main drawback to tires with tubes is the likelihood of getting a flat tire. Flat tires can happen in any number of ways - from the tube being pinched between the rim and the tire, from a deep puncture into the tire, or from a broken valve. Given the forces exerted on a downhill mountain bike wheel and frame during the course of a ride, it is entirely likely that any or all of those causes will cause a flat. A flat tire renders a downhill mountain bike unrideable - no one wants to ride just on their rims, as that damages rims beyond repair. Flat tires must be fixed as soon as possible, causing major delays in downhill mountain biking descents and races.
Another option when looking at downhill mountain biking tires, ont that reduces the possibility of a flat tire, are tubeless tires. Tubeless tires are a more recent innovation, but one that has gained acclaim and a mass following within the downhill mountain biking world. Tubeless tire systems use a strong adhesive to bond the tire to the frame of the wheel - air is then pumped directly into the tire, negating the need for any tubes. Pinch flats are rendered obselete, and, because most adhesives used in tubeless tire systems are so strong and resilient, puncture flats that could have previously crippled a downhill mountain bike are no longer a worry. Tubeless tire systems used to be much more expensive than tires with tubes, but now, as the technology is becoming more widely available, and adaptation kits which allow downhill mountain bikers to change their tube tires to tubeless tires in the comfort of their own home, the prices are much lower.