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).
Comparison chart of dimensions for standard and balloon tires.
| Identifier | ExFiles\Box 53\2\ Scan095 | |
| Date | 28th February 1924 | |
| Automotive Industries February 28, 1924 44565 513 Dimensions of Standard and Balloon Tires (Drawn to scale to afford comparison between present popular sizes and balloon sizes recently approved by the Rubber Association.) TIRES FOR 3½ IN. NOMINAL SIZE RIMS REGULAR SIZES 30x3½ CLINCHER SS{S. Smith} 30x3½ 4.40/20 29x4.40 4.40/21 29x4.40 4.40/22 30x4.40 5¼x4.40 INTERCH WITH 30x3½SS{S. Smith} TIRES FOR 5 IN. NOMINAL SIZE RIMS REGULAR CORD SIZES 30x5 33x5 35x5 6.60/21 33x6.60 INTERCH WITH 33x5 7.30/20 34x7.30 NOTE Tires which are stippled are balloon sizes approved by the Rubber Association Feb. 6, 1924. Approved nominal size marking is given above each tire. Figures for outside diameter of tires are approximate and vary with make of tire, thickness of tread, etc. * Starred size is width of 5 in. rim having a flange height equal to that of a 4½ in. rim. TIRES FOR 4 IN. NOMINAL SIZE RIMS REGULAR CORD SIZES 31x4 32x4 33x4 4.95/20 29x4.95 4.95/22 31x4.95 INTERCH WITH 31x4 5.25/21 32x4.95 INTERCH WITH 32x4 5.25/20 30x5.25 5.25/21 31x5.25 5.25/22 32x5.25 TIRES FOR 4½ IN. NOMINAL SIZE RIMS REGULAR CORD SIZES 29x4½ 32x4½ 33x4½ 34x4½ 5.77/20 30x5.77 5.77/21 31x5.77 5.77/22 32x5.77 INTERCH WITH 32x4½ 33x5.77 INTERCH WITH 33x4½ 34x5.77 INTERCH WITH 33x4½ 6.20/20 32x6.20 6.20/21 33x6.20 Handwritten notes: 6-60 33 x 6 3.75 | ||