Specification table for the Wide Base Rim Program, comparing present and experimental practices for various tire sizes.
| Identifier | ExFiles\Box 156\3\ scan0217 | |
| Date | 1st September 1940 | |
| WIDE BASE RIM PROGRAM (As of September 1940) Tire Size Present Practice Experimental Practice Recommended Permissible 5.50 3.50 D 4.00 E 4 1/2 L 5 L 6.00 4.00 E 4.50 E 5 L 5 1/2 L 6.25 4.25 E 4.50 E 5 L 5 1/2 L 6.50 4.50 E 5.00 E or F 5 1/2 L 6 M 7.00 5.00 E or F 5.50 F 6 M 6 1/2 M 7.50 5.50 F 6.00 F 6 1/2 M 7 N Flange Heights: L = 0.78" M = 0.84" N = 0.90" Approximate ratios of rim width to inflated section width for the above columns, reading from left to right, are 65%, 70%, 75% and 80%. | ||
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).