mammoth Posted February 22, 2022 Share Posted February 22, 2022 My current project with the 1911 Dennis fire engine will involve not just the building of wood wheels but the steel bands that tie those wheels tight and making of the press on tyres. The pressing off and on of hard rubber tyres is documented elsewhere in this forum but what makes for the correct interference fit? As it happens the new addition to the library - Mechanical Road Transport by Conradi, pub 1923 - has all the answers and the relevant chapter is below. In precis the wheel sizes which became the British standard are 670mm; 720; 771; 850; 881. American sizes are also provided and explained. Given that diameter measurements can be a bit wobbly the critical measurements are provided for wheel circumference and tyre internal circumference with the interference created by a tyre circumference at least 3mm less. There is a chart for the range of presures required to press on a tyre for each size etc Interestingly Conradi predicted that synthetic rubber would not catch on commercially to any great extent. hard TYRES specs.pdf 5 Quote Link to comment Share on other sites More sharing options...
radiomike7 Posted February 22, 2022 Share Posted February 22, 2022 Shame he spoils the publication by referring to the force required to fit a tyre as pressure in tons! Quote Link to comment Share on other sites More sharing options...
mammoth Posted February 22, 2022 Author Share Posted February 22, 2022 Mike, I can't see the problem with that, especially as all the surviving presses designed for the job would still be calibrated (if they were ever calibrated that is) in tons. The Americans are probably still using units of 1,000 lbs. I wouldn't know what a kilopascal was if it ran over me. haha. 3 Quote Link to comment Share on other sites More sharing options...
radiomike7 Posted February 23, 2022 Share Posted February 23, 2022 Pressure is force/area as in psi, you fit a solid tyre to a wheel using a force as in tons. Quote Link to comment Share on other sites More sharing options...
andypugh Posted February 23, 2022 Share Posted February 23, 2022 On 2/22/2022 at 6:56 AM, mammoth said: Given that diameter measurements can be a bit wobbly the critical measurements are provided for wheel circumference and tyre internal circumference with the interference created by a tyre circumference at least 3mm This turns out to be easier than you might imagine. There is a lot to be learned from Engels Coach Shop: Measuring wheels and tyres is only part of this. 50 seconds after the linked start you will know how to measure and size tyre bands. Also in this video is an example of pressing tyres on to wheels with a layer of canvas to tighten it up, which I have heard of used in our context too. Quote Link to comment Share on other sites More sharing options...
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