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).
Blueprint comparing dimensions and load ratings for four different tyre types and sizes.
| Identifier | ExFiles\Box 42\1\ Scan061 | |
| Date | 14th May 1926 guessed | |
| X3805 (X4685) 6.64" 16.15" EFFECTIVE RADIUS LOAD 15 1/2 CWTS AT 37 LBS/SQ. INCH. 17 3/8 CWTS AT 41 LBS/SQ. INCH. 35" DIA 66.17" CIRC. 21.065" DIA 33" x 6.75" BALLOON TYRE ON 5" x 21" RIM 6.12" 15.65" EFFECTIVE RADIUS LOAD 15 1/2 CWTS AT 45 LBS/SQ. INCH. 17 3/8 CWTS AT 55 LBS/SQ. INCH. 33.625" DIA 66.17" CIRC. 21.065" DIA 6" EXTRA HEAVY TYRE ON 5" x 21" RIM 5.88" 15.70" EFFECTIVE RADIUS LOAD 11 1/2 CWTS AT 34 LBS/SQ. INCH. 33.65" DIA 66.17" CIRC. 21.065" DIA 33" x 6.00" BALLOON TYRE ON 4 1/2" x 21" RIM 5.37" 15.18" EFFECTIVE RADIUS LOAD 11 1/2 CWTS AT 48 LBS/SQ. INCH. 32.45" DIA 66.17" CIRC. 21.065" DIA 5 1/4" EXTRA HEAVY TYRE ON 4 1/2" x 21" RIM | ||