Tire Flaps
The tire flap protects the inner tube from the valve slot of the rim and from the edges of the tire bead toe to prevent the tube from chafing, pinching, and cracking. The flap also controls the valve stem protrusion through the rim.
Valve hole reinforced flaps are required with truck tires to reduce flap push-through, since such tires are normally run at pressures of 90 psi or greater. Reinforced flaps made from special rubber compounds are required with all radial tires because of the higher inflation pressures and the greater tire sidewall flexing characteristic of radials. Either of these reinforced flaps may be used with standard ply bias tires. Reinforcements may be an extra layer of rubber, a fabric patch, metal insert, or other devices. Flaps designed for bias tires should not be used in radial tires.
New flaps should always be used with new tires. Flaps should remain mated to the original tires, since they grow to the shape of that tire. Damaged flaps, including heat-embrittled ones, should not be reused.
Contacting surfaces of the rim, flap, tube, and tire should be lubricated with a material conforming to RP 205C, Tire Bead Lubricants, for proper assembly and to minimize component displacement.
See RECOMMENDED RIM AND FLAP WIDTHS -2 for a listing of tube-type tire section widths, bead diameters, design rim widths and corresponding recommended flap widths for Class 6-8 commercial vehicles.
- Radial ply tires require tubes and flaps designated for radial use.
- Tube size designation is the same as tire size designation.
- With alternate wide rims (1/2" wider), use the next wider flap if available. With alternate narrow rims (1/2" narrower), use the indicated flap.
- Flap widths designated are generally correct. However, some tire manufacturers recommend narrower flap widths, while others recommend wider. Consult your tire supplier for a recommendation.
- All truck rims, wheels and tires are rated for maximum load and inflation pressures by the manufacturer in accordance with standard industry test procedures. Maximum load and cold inflation pressure are usually stamped on the rim/wheel and always on the tire. Consult your supplier if questions arise.
| Tire Size | Design Rim Width | Minimum Flap Width | |
|---|---|---|---|
| Width | Diameter | ||
| 7.50 | 15TR | 6.00 | 6.5 |
| 20 | 6.00 | 6.5 | |
| 8.25 | 15TR | 6.50 | 7.0 |
| 20 | 6.50 | 7.0 | |
| 9.00 | 15TR | 7.00 | 7.0 |
| 20 | 7.00 | 7.0 | |
| 10.00 | 15TR | 7.50 | 7.5 |
| 20 | 7.50 | 7.5 | |
| 22 | 7.50 | 7.5 | |
| 11.00 | 15TR | 8.00 | 8.0 |
| 20 | 8.00 | 8.0 | |
| 22 | 8.00 | 8.0 | |
| 24 | 8.00 | 8.0 | |
| 12.00 | 20 | 8.50 | 8.0 |
| 24 | 8.50 | 8.0 | |
| 335/80 | 20 | 9.00 | 10.0 |
| 365/80 | 20 | 10.00 | 10.0 |
| 365/85 | 20 | 10.00 | 9.0 |
| 395/85 | 20 | 11.00 | 9.0 |
Source: Tire & Rim Association
| Tire Size | Design Rim Width | Minimum Flap Width | |
|---|---|---|---|
| Width | Diameter | ||
| 13.00R | 20 | 9.00 | 8.00 |
| 14.00R | 20 | 10.00 | 9.00 |
| 21 | 10.00 | 9.00 | |
| 24 | 10.00 | 9.00 | |
| 25 | 10.00 | 9.00 | |
| 16.00R | 20 | 11.25 | 9.00 |
| 21 | 11.25 | 9.00 | |
Source: Tire & Rim Association