From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Standard chart for tire and rim specifications and markings.
| Identifier | ExFiles\Box 42\5\ Scan052 | |
| Date | 17th January 1929 | |
| TIRE AND RIM STANDARD A12177 Tire Cross Section Rim Dia. | 4.50 | 4.75 | 5.00 | 5.25 | 5.50 | 6.00 | 6.50 | 7.00 18 | | | | | 5.50-18 Replaces 28 x 5.50 | 6.00-18 Replaces 30 x 6.00 | 6.50-18 Replaces 30 x 6.50 | 7.00-18 Replaces 30 x 6.75 32 x 7.00 19 | | | 5.00-19 Replaces 28 x 5.00 | 5.25-19 Replaces 29x 5.25 | 5.50-19 Replaces 29 x 5.50 | 6.00-19 Replaces 31 x 6.00 | 6.50-19 Replaces 31 x 6.50 | 7.00-19 20 | | 4.75-20 Replaces 29 x 4.75 | 5.00-20 Replaces 30 x 5.00 28 x 4.95 | | 5.50-20 Replaces 30 x 5.50 | 6.00-20 Replaces 32 x 6.00 30 x 5.77 | 6.50-20 Replaces 32 x 6.50 | 7.00-20 Replaces 32 x 6.75 34 x 7.00 21 | 4.50-21 Replaces 30 x 4.50 | | | | | | | Rim Section Width | 2.75 Flat Base or Drop Center | 4" | 4" | 4" | 4-1/2" | 4-1/2" | 5" Max. Tire Width on Rims | 4.75 | 4.85 | 5.15 | 5.35 | 5.60 | 5.95 | 6.40 | 6.90 Rim widths given are nominal except the 2.75-in. size, which dimension is the actual width between flanges. METHOD OF MARKING Tires shall be marked with the tire cross-section followed by the rim diameter on which the tire shall be used. Under this designation shall be placed in smaller type the word, "Replaces" followed by the former name size of the tire. Tires shall be marked for balance by means of a red dot or a 1/4" square on the serial of the casing just above the rim flange. Revised Jan. 17/1929. STAMP: FEB 27 1929 A12177 | ||