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 diagram showing profiles, dimensions, and load ratings for four different tyres.
| Identifier | ExFiles\Box 53\2\ Scan204 | |
| Date | 1st April 1926 guessed | |
| Handwritten: X4565, (X3809) Top Left Diagram: Dimensions: 6.64", 35" DIA, 66.17" CIRC., 21.063" DIA 16.15" EFFECTIVE RADIUS LOAD 15 1/2 CWTS AT 37 LBS/SQ. INCH. 17 3/8 CWTS AT 41 LBS/SQ. INCH 33" x 6.75" BALLOON TYRE ON 5" x 21" RIM Top Right Diagram: Dimensions: 6.12", 33.625" DIA, 66.17" CIRC., 21.063" DIA 15.65" EFFECTIVE RADIUS LOAD 15 1/2 CWTS AT 45 LBS/SQ. INCH. 17 3/8 CWTS AT 55 LBS/SQ. INCH. 6" EXTRA HEAVY TYRE ON 5" x 21" RIM Bottom Left Diagram: Dimensions: 5.88", 33.65" DIA, 66.17" CIRC., 21.062" DIA 15.70" EFFECTIVE RADIUS LOAD 11 1/2 CWTS AT 34 LBS/SQ. INCH 33" x 6.00" BALLOON TYRE ON 4 1/2" x 21" RIM Bottom Right Diagram: Dimensions: 5.37", 32.45" DIA, 66.17" CIRC., 21.062" DIA 15.18" EFFECTIVE RADIUS LOAD 11 1/2 CWTS AT 42 LBS/SQ. INCH 5 1/4" EXTRA HEAVY TYRE ON 4 1/2" x 21" RIM | ||