This is a pair of Pitbull 1.9" Rock Beast XL Crawler Tires. The Rock Beast XL is similar to the original Rock Beast but now sports a larger size for guys wanting tall 1.9 tires. The extra size from the XL's put them at the max 4.75" diameter; the originals on the other hand stand at 4.45". Pit Bull Multi-Varied Tread Design Pit Bull multi-varied tread design increases forward/reverse and lateral traction with serious biting across the footprint. These Rock Beasts have many features designed to increase speed and control while enhancing stability and contact patch. Excellent lateral bite--incredible stickiness and exceptional traction. Alien Kompound Alien Kompound is a super sticky rubber compound, and as they say at Pit Bull, they're "Stickier than Alien Snot!" Alien Kompound is great for wet or dry and provide great holding power even in off-camber terrain. Features ALIEN Kompound is the only compound Pit Bull is using on these tires. They seem to get better and better as they break in... and you can