Selecting the Perfect Mountain Bike Tire
So before you plunk down your hard earned cash for a new set of tires take a moment to understand the properties that affect tire performance.
Primary performance factors are: Traction, Durability, Ride Quality, Braking, Rolling Resistance.
There are two wheel diameters for mountain bikes which.
1) The traditional 26″ Wheel
2) The increasingly popular 29″ wheel.
Benefits of the 29″ are better traction and braking due to a larger contact patch.
Width is another story, much like women’s clothing, tire width designation can vary by manufacturer and tire model.
1.8-2.0 Light Trail and XC Racing
2.0-2.3 Aggressive XC and All-Mountain
2.4-3.0 Downhill and Free-Ride
In general a wider tire will provide a smoother more subtle ride, a more narrow tire will have less rolling resistance.
The trick is finding the sweet spot for your type of riding.
Next we will look at the tires casing. This weaved thread is what makes up the foundation of the tire. Threads per inch (TPI) can range from 30-300. The higher the count the better the quality. (think bed sheets) A higher thread count will positively affect tire weight, traction, and puncture resistance.
Tread: The more aggressive the tread the better the traction and cornering. But there is a trade-off between traction and rolling resistance.
Tread spacing and depth: Wide spaced treads shed mud and debris.
Deeper knobs maintain better traction when riding in loose and/or muddy conditions, but have greater rolling resistance when riding on hard-pack surfaces.
A tight tread pattern with shallow knobs will roll well in hard-pack conditions but traction suffers in loose and muddy conditions.
There are a number of tread patterns designed to fit your riding style.
- Slick: Asphalt, commuting.
- Inverted-Tread: Asphalt light trail, rough commuting.
- Semi-slick: Dirt paths and Light trail riding.
- Knobbies: Trail riding, Downhill, and Free-ride.
Durometer: Natural rubber is sticky and unstable. So a process called vulcanization is used to make the rubber more suitable for use in Bike Tires. By adding Sulfur or other polymers and cooking, manufactures can create rubber that is as hard or soft as they require.
Tire hardness is measured in Durometer, the higher the number the harder the rubber and the more durable the tire. Most tires range in Durometer from 42 to 70. Higher durometer tires roll fast but sacrifice traction, especially in wet conditions. A 42 durometer tire will have great traction but wear quickly and roll slow, most tires will fall in between. Better, more expensive tires often will have a dual or triple compound of around 55 for the center knobs and 45 for the side.
Directional and Front/Rear specific Tread:
Directional Tires have tread designed to run in a specific direction usually with ramped knobbies and/or a chevron pattern that performs optimally in a one direction or another. The mounting direction of the tire is usually noted on the sidewall of the tire.
Front/Rear specific tires – Front tires are designed for carving turns with better traction when cornering.
Rear tires are designed to provide optimal power transmission and rear wheel control.
Wire Bead tires are less expensive and heavier than their Aramid bead counterparts but generally stay on the rim even at low tire pressure
Aramid Bead Tires are more expensive but lighter up to a 100 grams but run a greater risk of coming off the rim during a flat. (Also known as Kevlar or folding bead tires)
Tube vs Tubeless
Tubed tires require an inner tube to hold air. Bike tubes have two valve types: Schrader and Presta the one that you require is determined by your rim type.
Schrader valves are the same as the valve on most cars. Presta valves have a long skinny metal shaft with a threaded top. Pros of tubed tires – Generally less expensive easier to repair flat on the trail. Cons – Prone to pinch flats.
Tubeless tires allow you to ride at a lower pressure providing better traction without pinch flats.
Tubless Tire Systems:
UST – Universal System for Tubeless set standards for rim and tire manufacturers to work towards. UST compatible systems allow you to install the tire by hand and inflate with a standard floor pump. The tires have an extra layer of rubber inside the carcass to seal against leaks. They do not have to be used with a liquid sealant.
Tubeless ready systems and the use of Rim strips can benefit from the use of No Tubes Stan’s Tire Sealant.
I have used Stan’s on both Mavic UST wheels and Shimano tubeless ready wheels to guard against flats, however some tire manufacturers warn against this. And use of a sealant and will void the tires warranty.