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).
Table of proposed new American tire and rim sizes to replace existing equipment.
| Identifier | ExFiles\Box 158\1\ scan0050 | |
| Date | 10th March 1928 guessed | |
| TABLE OF PROPOSED NEW AMERICAN TIRE SIZES 16 SIZES TO REPLACE PRESENT 24 SIZES AS ORIGINAL EQUIPMENT RIM SIZES New Nominal Tire Section | Actual Present Practice | Present Nominal Section | Nominal | Present Width between flanges | New width between flanges --- | --- | --- | --- | --- | --- 4.50 | 4.75 | 4.50 | (2.754" wellbase) | 2.75" | 2.75" 4.75 | 4.95 | 4.75 | 4" | 2.68" | 2.75" 5.00 | 5.20 | 5.00 | 4" | 2.68" | 2.75" 5.25 | | 5.25 | 4" | 2.68" | 2.75" 5.50 | 5.65 | 5.50 | 4" | 2.68" | 2.75" 6.00 | 6.10 | 6.00 | 4-1/2" | 3.125" | 3.25" 6.50 | 6.55 | 6.20 | 4-1/2" | 3.125" | 3.25" 7.00 | 7.00 | 6.75 | 5" | 3.75" | 3.75" | | 18" | | 19" | | 20" | | 21" | --- | --- | --- | --- | --- | --- | --- | --- | | Present Name | New Name | Present Name | New Name | Present Name | New Name | Present Name | New Name --- | --- | --- | --- | --- | --- | --- | --- | 4.50| | | | | | | 30x4.50 | 30x4.50 4.75| | | 28x4.75 | 28-1/2x4.75 | | | | 5.00| | | 29x5.00 | 29x5.00 | 30x5.00 | 30x5.00 | | 5.25| 28x5.25 | 28-1/2x5.25 | 29x5.25 | 29-1/2x5.25 | | | | 5.50| 28x5.50 | 29x5.50 | 30x5.50 | 30x5.50 | 30x5.50 | 31x5.50 | | 6.00| 30x6.00 | 30x6.00 | 31x6.00 | 31x6.00 | 32x6.00 | 32x6.00 | | 6.50| 30x6.20 | 31x6.50 | 31x6.20 | 32x6.50 | 32x6.20 | 33x6.50 | | 7.00| | | | | 32x6.75 | 34x7.00 | | Sizes cancelled (present nomenclature) (These sizes are in present current production) 29 x 4.75 - 20" wheel 30 x 5.25 - " 31 x 5.25 - 21" wheel 33 x 6.00 - " 33 x 6.20 - " 30 x 6.75 - 18" wheel 31 x 6.75 - 19" wheel 33 x 6.75 - 21" wheel | ||