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Tech. Advice: Series 'B' / 'C' 500cc/1000cc Bikes
Avon Speedster tire?
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<blockquote data-quote="GBewley" data-source="post: 50993" data-attributes="member: 583"><p>I received the following today from Avon Tyres. I think they missed the fact I was speaking of two separate and different tires, but I am pleased to have gotten this much! For our collective edification:</p><p></p><p>----------------------------------</p><p> </p><p>3.00-20 Avon Speedster</p><p> </p><p>I have delved in the archives and, Bingo, managed to find the old tyre specifications for Avon Speedster, the</p><p>earliest dating from 8th December 1933 and the latest dated 15th September 1954 when the Speedster range</p><p>was cancelled and superseded by the Speedmaster range.</p><p> </p><p>Tyre sizes comprised: 3.00-19, 3.25-19, 3.50-19, 3.00-20, 2.75-21 and 3.00-21.</p><p> </p><p>The simple tyre construction was 4 plies of rayon at 37.5º bias angle with a 2 up 2 down tie-in, a 3/2 bead</p><p>stack, and 1” wide fabric chafers, with a natural rubber tread.</p><p> </p><p>The mould number for 3.00-20, the size in question, was 7394. The mould drawing number was TD34 and the</p><p>curebag TDS274. (An earlier version from 1941 quoted mould drawing PT8030). Interesting to note that the</p><p>mould rings were stamped 26 x 3.00.</p><p> </p><p>The specifications state that two tinplate stencils were required – a serial number stencil measuring 1.25” x 5/16”</p><p>and a date code stencil measuring 1½” x 5/16” both with semi-circular ends.</p><p> </p><p>Also mentioned was the requirement in the 1940’s for a stencil denoting “R” and another denoting “D” and a</p><p>sticker applied in the wrapping room to also denote “R”. (At one time finished tyres were spirally wrapped with</p><p>brown paper). It is not known what these signified.</p><p> </p><p>A couple of the specifications quoted “4G26 tread reserved for HRD covers only”, I seem to remember that the</p><p>Vincent HRD was a make of motorcycle famed in the 1940’s as ‘the world’s fastest production motorcycle’ – there</p><p>may or may not be a connection.</p><p> </p><p>When we look at the date codes neither “NIC” or “EIO” fit the cipher in use prior to 1956 unless there was a</p><p>different earlier cipher of which I have no knowledge. “NIC” would fit the post 1956 cipher but the tyres were</p><p>no longer in production then, and deciphering the code produces a date of June 1987 which is impossible. In the</p><p>case of “EIO” the E does not fit with the later cipher and the O does not fit with the earlier cipher. So I remain</p><p>puzzled and can only hazard a guess that these tyres were produced in the 1940’s or early 1950’s.</p><p> </p><p>I could find no reference to “VA7477” and can only assume that “510152” was a serial number.</p><p> </p><p>That’s about it.</p></blockquote><p></p>
[QUOTE="GBewley, post: 50993, member: 583"] I received the following today from Avon Tyres. I think they missed the fact I was speaking of two separate and different tires, but I am pleased to have gotten this much! For our collective edification: ---------------------------------- 3.00-20 Avon Speedster I have delved in the archives and, Bingo, managed to find the old tyre specifications for Avon Speedster, the earliest dating from 8th December 1933 and the latest dated 15th September 1954 when the Speedster range was cancelled and superseded by the Speedmaster range. Tyre sizes comprised: 3.00-19, 3.25-19, 3.50-19, 3.00-20, 2.75-21 and 3.00-21. The simple tyre construction was 4 plies of rayon at 37.5º bias angle with a 2 up 2 down tie-in, a 3/2 bead stack, and 1” wide fabric chafers, with a natural rubber tread. The mould number for 3.00-20, the size in question, was 7394. The mould drawing number was TD34 and the curebag TDS274. (An earlier version from 1941 quoted mould drawing PT8030). Interesting to note that the mould rings were stamped 26 x 3.00. The specifications state that two tinplate stencils were required – a serial number stencil measuring 1.25” x 5/16” and a date code stencil measuring 1½” x 5/16” both with semi-circular ends. Also mentioned was the requirement in the 1940’s for a stencil denoting “R” and another denoting “D” and a sticker applied in the wrapping room to also denote “R”. (At one time finished tyres were spirally wrapped with brown paper). It is not known what these signified. A couple of the specifications quoted “4G26 tread reserved for HRD covers only”, I seem to remember that the Vincent HRD was a make of motorcycle famed in the 1940’s as ‘the world’s fastest production motorcycle’ – there may or may not be a connection. When we look at the date codes neither “NIC” or “EIO” fit the cipher in use prior to 1956 unless there was a different earlier cipher of which I have no knowledge. “NIC” would fit the post 1956 cipher but the tyres were no longer in production then, and deciphering the code produces a date of June 1987 which is impossible. In the case of “EIO” the E does not fit with the later cipher and the O does not fit with the earlier cipher. So I remain puzzled and can only hazard a guess that these tyres were produced in the 1940’s or early 1950’s. I could find no reference to “VA7477” and can only assume that “510152” was a serial number. That’s about it. [/QUOTE]
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Tech. Advice: Series 'B' / 'C' 500cc/1000cc Bikes
Avon Speedster tire?
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