Product User Information
CTS (Contact Tire System) — Overview
The BGR Tires CTS is a patented dual-chamber tire system designed to meet five core requirements:
1. Puncture-proof — not merely puncture-resistant
2. Pinch-proof — with any BGR CTS and tire combination
3. Impact absorption — reduces wheel deflection and bounce when striking rocks and roots
4. Steering performance — increases directional stability and accuracy by raising sidewall pressure; the CTS effectively reduces sidewall height controlled by air pressure by ~25mm while the outer chamber absorbs impacts via soft silicone rubber
5. Lightweight — reduces unsprung weight on Moto and MTB applications
System Components
The CTS contains three internal components:
1. Rock Shield (Outer Chamber) Made of silicone rubber in various durometers. Guards against thorns, nails, sharp rocks, and other penetrating objects.
2. Tire Insert A self-centering, non-elastomeric barrier made of lightweight butyl rubber and nylon and/or Aramid (Kevlar-type) material. It sits between the outer chamber and the inner tube. The insert crown is engineered not to swell into the outer chamber volume, keeping the Rock Shield's behavior independent of inner tube pressure. This lets the rider select Rock Shield softness and inner chamber PSI independently.
Note: At inner chamber pressures above 20 PSI, minor insert crown swelling may occur — similar to an overinflated car tire. Rather than causing uneven wear, this effectively increases the outer chamber's durometer and firmness.
3. Inner Tube (Inner Chamber) Standard inner tube. Works in conjunction with the Tire Insert to resist movement and increase sidewall stability.
Mounting Instructions
Step 1 — Install Rock Shields Place and center the 9 Rock Shield pieces inside the tire (LW or any 3.0–3.5 × 21 front tire). Apply silicone lubricant to the inner tire carcass and the outer face of each Rock Shield piece to improve performance and extend lifespan. Recommended lubricants: WD-40 Silicone or B'Laster Silicone.
Step 2 — Install Tire Insert Place the Tire Insert inside the tire. Check the full perimeter to confirm the insert crown edge seats inside the Rock Shield shoulder on both sides. This is a zero-tolerance fit. Do not lubricate these surfaces.
Step 3 — Mount first bead Mount one tire bead onto the rim. The LW tire can be mounted by hand with soapy water.
Step 4 — Prepare inner tube Lightly inflate the inner tube to give it shape. Do not apply baby powder to the inner tube or Tire Insert — you want them to act as a unified unit when inflated, working against the outer chamber to minimize movement and maximize sidewall stability.
Step 5 — Insert inner tube Install the inner tube and seat the valve stem.
Step 6 — Mount second bead and inflate Mount the remaining bead, noting how the Tire Insert protects the tube from tire irons. Apply a small amount of bead lube or soapy water to seat the bead. Inflate to 18–21 PSI for initial testing, then reduce pressure to compare feel. A rim lock is not required above 14 PSI.
Low-Pressure Operation
The CTS is validated for use above 14 PSI. Below that threshold, the Rock Shield may shift laterally in the outer chamber, violating the Tire Insert and creating wheel imbalance.
If operation below 15 PSI is required:
- Apply silicone lubricant and contact adhesive between the Tire Insert and each Rock Shield piece
- Use a larger, heavier inner tube (available on the BGR Tires website) for increased sidewall support and surface tension against the insert
- Be aware that pinch flat risk increases at lower pressures
This configuration is suitable for hard enduro riders who prioritize shock absorption and can accept the additional weight.
BGR Tires LW 80/100-21 Front Tire
The LW (Lightweight) front tire is designed to complement the CTS system and is compatible with all standard mousse systems. It weighs 1.8 lbs less than the Dunlop equivalent. Due to its softer, lighter construction, a minimum of 16 PSI is required for optimal performance in most MX and off-road conditions.