Lets start with width. The XR, and in fact most current muds, are predominantly around the 2.0 width, and the same with these new ones. Why is this?

In wet–muddy conditions you typically do not want a wide tyre, the wide tyre tends to slide around on top of the mud, instead of biting into the mud to find traction. Muddy terrain can get very rutted and the wide tyre doesn’t fit easily into the ruts, which can cause the bike to cross rut making it difficult to keep it in the line you are choosing. Plus the wider the tyre, typically the more mud the wheels carry, making the bike feel very heavy and increase rolling resistance.

The new casing stiffness is very similar to the current version, but we have a new material for our Inner Strength sidewall which has higher cut resistance and is lighter. It’s very effective when using low tyre pressure and seals tubeless amazingly well.

The previous XR Mud was 62a/60a compound… 62a centre and 60a shoulder. We are continuously developing rubber compounds throughout the Bontrager tyre line. The new XR Mud is a prefect example of our hard work. We’ve developed a faster rolling centre rubber with higher traction and a softer rubber in the transition knobs/shoulder knobs for higher cornering traction. Plus it’s lighter weight.

The durometer is 62a/50a on the new tyre but please remember the rubber compound performance is not based on durometer alone. There are several factors and properties to consider when making a rubber compound. There’s the polymer, oils, carbon black/silica and others… all of which have an effect on the rubber compound performance and durometer. It’s much like making a cake to eat and the outcome depends on the ingredients and the percentages of those ingredients.

Correct, the rubber is a key part but only one part of the puzzle. Tread pattern, casing structure and weight all play a key roll to the finished product. It’s about finding the proper balance between all the parts.

Very similar to the current XR Mud. However, we’ve sharpened up the knob edges and angled the shoulder knob both to increase traction and to help shed mud. The shoulder knob angled edge is designed to move the mud away from the contact patch easier. The small high sidewall knobs (between the shoulder knobs) help find traction in rutted areas.

Rolling resistance is improved considerably how have you achieved this?

We definitely reduced rolling resistance on the new tyre. It’s a combination of tread shape, tread spacing, rubber compound, casing structure and lighter weight. We’ve been able to find a good balance between all these key points.