Twenty Nine Inches has obtained a pair of Bontrager XR-1 29 inch tires for testing. These are listed as a 1.9″ width tire and are aimed at racing cross country style. The tire has a goal of being fast. light, and supple in terms of the casing. To that end, it is not a Tubeless Ready model.

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While the tire may not be rated as a tubeless ready model, I did mount them in this manner to a first generation Bontrager Race X Lite wheel with the TLR rim strip installed. I used a mixture of CaffeLatex and Slime tubeless sealant to do this and had zero issues inflating and seating the tire on the rims. No leaking down so far and I suspect the tires will do fine in this configuration. Just be aware that I have undertaken this at my own risk and we at Twenty Nine Inches can not condone the use of this tire tubeless. It does void any warranties as well. However; being also realists, and knowing that folks are already running these tires tubeless, we will be doing the testing as such. (Note: These tires were purchased by the tester with his own money and said tester assumes all risks involved. Don’t try this at home on account of me!)

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Bontrager describes the XR-1 as follows: (from the Bontrager site)

Designed in collaboration with Bontrager-sponsored pro race team riders, the XR1 is an ultra-fast rolling cross country race tire that’s ideally suited for dry and dusty condition. Small, tightly spaced knobs provide plenty of fast-rolling traction, while siping (thin slits) across the middle knobs give even more grip on dusty surfaces. Designed for front or rear use.

Furthermore; the tire features a 120 TPI casing, and several rows of very small square blocks with a very “crowned” profile. This is a tire very reminiscent of another favorite of 29″er riders from Kenda, but that tire is flattened a bit more in profile than the XR-1. The “Team” model is listed as a 1.9″ width, or 48mm knob to knob outer width and 46mm casing width. Weight is listed as being 495 gm. Here are my measurements from my samples, both mounted on 24mm wide rimmed Race X Lite wheels tubeless.

Width Of Casing……………….45.0mm
Knob To Knob………………….47.2mm
Height Of Casing………………41.3mm
Weight………………………….480gm/490gm (pair)

I’ll be hitting some dry, dusty courses in the coming weeks and also will follow up with some other race type tire reviews that have been put on hold due to our extended wet period here in the Mid-west. Stay tuned!

Note: These tires were purchased by the tester for review on Twenty Nine Inches. We are not being paid, nor bribed for this review. We strive to give our honest opinions and thoughts throughout.