Richard Peskett Posted March 1, 2011 Share Posted March 1, 2011 Quite a lot has been written recently about the sizes and fitting of solid tyres so I hope this will explain and clarify some of the points raised. Sizes : Tyres always fell into two categories, American with all sizes in imperial measurement, UK / Continental virtually all sizes in metric. This may have been because pre 1910 a very high pecentage of commercial vehicles in use here were of continental origin ( some 700 De Dion & Milnes-Daimler buses running in London by 1907 ). By 1913 a situation of near chaos was approaching with dozens of different sizes being used by manufacturers. In mid 1913 a committee was set up by the SMMT to investigate this and produce a resolve. The outbreak of WW1 hastened this and in July 1915 as a basis for a new British Standard it was suggested that the 173 different rim sizes should be reduced to 6 and with universal tolerances to be used. All rim circumferences had a set minimum / maximum variation of 3mm. New sizes to be adopted were to be rim sizes of 670, 720, 741, 771, 850 and 881mm of which 670 and 741mm were to be dropped as soon as practical. Interestingly 670 was a popular steam wagon front size and 741 was widely used on the LGOC 'B' type buses, probably the largest users pre WW1. American sizes remained standard for rims size 26,28,30 and 34". Virtually all WW1 trucks had 30" front and 34" rear, e.g. marked 36 x 6 for 30" or 40 x 6 for 34". Another anomaly was that all imperial tyres were the same o.d. when new irrespective of width, e.g. 30" rim = 36" o.d. tyre and 34" rim = 40" o.d. tyre. Not so with the metric spec., with these the o.d. of a new tyre varied in diameter according to the width. e.g. a tyre would be marked in 3 dimensions, 880 x 120 for 720mm or 870 x 100 for 720mm. I will follow in due course with tyre presses, pressing on and usage. Richard Peskett. Quote Link to comment Share on other sites More sharing options...
nz2 Posted March 3, 2011 Share Posted March 3, 2011 Good to see another specialist thread being formed. Thanks Richard. We have here an example for how to fit differing tyre diameters to a smaller rim diameter. Wheel is 720 mm where as the tyre is 765 or 30". Would appear to be a British wheel and American tyre, and a local conversion. Uncertain what the packing timber is but it appears to have held up well. Whether they would stand up to road use is another point! The name Ransomes painted on the inside of the wheel is an interesting feature. I assume made for the war effort. Too small for the rear of a steam wagon. Doug Quote Link to comment Share on other sites More sharing options...
8_10 Brass Cleaner Posted March 3, 2011 Share Posted March 3, 2011 (edited) Doug, they are Thornycroft J wheels arn't they? 670's were also popular on trailers. I have a 1/2 share in a approx 1910 Eagle on 670x160, also a 1920's Carrimore on the same size. 7 of the 8 tyres are best part knackered and I have one new 670x180 as a spare. There is another in the back of the Sentinel in the Science museum, but getting it past the Gurkhas on the gate may be problematic........ The Ransommes I mentioned was on 850 rears, but with packing for the imperial tire, there was only an inch or so of rubber left so I have no idea what size they were, but I believe they had to be cut off. some old stock 850 rings were bought but they were all different makers so the rubber was skimmed up in a big lathe to make them all the same. They were pressed on using the inside leg of a crane, with a 40foot container hanging off the jib, don't ask, Turbo is mad as a box of frogs! Edited March 3, 2011 by 8_10 Brass Cleaner Quote Link to comment Share on other sites More sharing options...
nz2 Posted March 4, 2011 Share Posted March 4, 2011 Doug, they are Thornycroft J wheels arn't they? Correct as to the truck they are for.One of a number of pre 1920 restoration projects here. Interesting in looking through photos both of past and recent trucks and parts, is the differences in patterns in the hole structure. For Thornycroft I've noticed 3 different patterns of disc wheels, a circle of holes and two of different triangular pattern setting for the outer holes. Same for the Leyland pattern of Military wheels with variations to the hole arrangement or no holes. Like the earlier photos of the labeled Ransomes wheels some of these variations could well be from other manufacturers supplying material for the War Dept. It's also a challenge to date items with spoked wheels. Variations within a manufacturer for years or models and so much for standardization. Doug Quote Link to comment Share on other sites More sharing options...
BenHawkins Posted March 4, 2011 Share Posted March 4, 2011 Richard, Thanks for the information, I look forward to seeing this thread progress. When I looked at the maths for elastic deformation of the tyre band it appeared that with the 3mm tolerance on the wheels meant that the tyre would most likely plastically deform when pressed onto the wheel (ie. it would be bigger if you pressed it off again). This means when remoulding tyres it is best to put them back on the wheel they were removed from. Ben Quote Link to comment Share on other sites More sharing options...
Old Bill Posted March 4, 2011 Share Posted March 4, 2011 The last user certainly got his money's worth out of those tyres! We have pressed an old band off of a wheel that had come from Australia and which had been fitted using timber as shown here. We thought that it would be straightforward to remove but it was a nightmare and took well over 100 tons to shift. Steel on steel was much easier. I am very interested to see the Ransomes name on the back of the wheel. I always thought that Thornycrofts bought their wheels from Taskers of Andover, just up the road but you live and learn. Interestingly, the Dennis front wheels were stamped, one 'S & C' and the other 'R S & J'. I take these to be 'Shrewsbury and Challoner' and ' Ransomes Sims and Jefferies'. It looks like Ransomes spent the war making components for other prime contractors. I wonder who made all of those great traction engine style wheels for the big guns. Does anybody know? Steve Quote Link to comment Share on other sites More sharing options...
8_10 Brass Cleaner Posted March 5, 2011 Share Posted March 5, 2011 I've just bought 4 tyres that will bore out to fit 670 rims. Anyone know what the interferance fit should be?. They currently have centres, as they are 1950's tank idlers. The guy who has them has just made a 120ton press to put some 5foot rings on Quote Link to comment Share on other sites More sharing options...
Richard Peskett Posted March 6, 2011 Author Share Posted March 6, 2011 Part 2. Manufacture. All solid tyres came complete on the steel backing band, usually about 1/2 " thick, ready to be pressed on. First problems came early on in attaching the rubber to the steel band. A tyre band I removed from a 1907 Milnes-Daimler 'bus wheel gave an interesting insight into how this was done. The steel band had holes through it and the top surface had radial 'dovetail' maching in it. The rubber completely encased the band. The band could only be described as a reasonable fit to the wheel rim and was held in place with a steel loose ring each side bolted through the wheel rim therefore centralising the tyre band and holding it on. Later a process of bonding the rubber to the steel band was developed alleviating the necessity of retaining bands although sometimes a register was cast as part of the wheel rim, the tyre being pressed on up to it and narrow retaining clamps bolted onto the opposite side. The use of a register on one side solved the problem of centring the tyre on the wheel as usually the tyre overhung the rim by about 10mm each side. Gaps were left in the register to enable the band to be pressed off. The 'dovetail' machining was still used on the band surface. More recently improved adhesives have eliminated the use of dovetailing. Each size trye had a specific weight of rubber used. This came in strip form about 1/8" thick . The prescribed weight would be wound around the steel band , placed in a cast iron mould, this being in two halves hence often on a new tyre a mould line can be seen around the circumference of the tread. The entire is then placed in an autoclave and heated to the prescribed temperature when the rubber becomes one homogeneous mass, the mould has lettering cast into it which subsequently appears as raised lettering on the side of the tyre. A more recent process is similar but a mould is not used , heating is critical so as the rubber does not 'run away' and the product has to be machined to profile. Presses, fitting and usage to follow. Richard Peskett. Quote Link to comment Share on other sites More sharing options...
Adrian Barrell Posted March 6, 2011 Share Posted March 6, 2011 I've just bought 4 tyres that will bore out to fit 670 rims. Anyone know what the interferance fit should be?. They currently have centres, as they are 1950's tank idlers. The guy who has them has just made a 120ton press to put some 5foot rings on I'm sure they are Cent or Chieftain with 10 stud holes but just in case...... If they are 8 stud, please do not cut the middles out, I will swap them for 10 stud plus cash if need be! Quote Link to comment Share on other sites More sharing options...
8_10 Brass Cleaner Posted March 7, 2011 Share Posted March 7, 2011 I'm sure they are Cent or Chieftain with 10 stud holes but just in case...... If they are 8 stud, please do not cut the middles out, I will swap them for 10 stud plus cash if need be! not seen them yet, thay originally came via Hirsts of St Mary Bourne. I expect 10 stud. Quote Link to comment Share on other sites More sharing options...
jhooah Posted April 4, 2011 Share Posted April 4, 2011 (edited) Well if anyone had a line on a set of press on tyres for my 1917 Standard B (Liberty) I will attempt to restore I would LOVE the hear about them. The rears are US: 40 x6 Double tyred with metal rise in between the riged rims, and 36 x 5 inch front wheels. As they are all cast steel wheels and very heavy, sending away to a shop or such is not the best of solutions. I was wondering if anyone had success with a Forklift Tire (tyre) casting company or such to utilize polyurethane either onto the rim or ordered to size so we could press fit them. I have a 120Lb press in my yard that can handle the operation after I fabricate a suitable ring and backing plate to both press potential rims on, and support the wheel underneath during the process. What would the metric equivalent of these be? I read above were talking 30" and 34" rims, be these do not easily transcribe into the metric sizes as posted above 762 x 127mm and 836.6 x152mm Kindest regards W Winget Carrollton, Virginia. william.winget (at) JFCOM (dot) mil see WWW.VMPA.US for some photo's of the truck, or on 'webshots' photo section http://good-times.webshots.com/album/565571364MinFRZ Edited April 4, 2011 by jhooah spelling argh! Quote Link to comment Share on other sites More sharing options...
Great War truck Posted April 5, 2011 Share Posted April 5, 2011 We have some polyurethene ones on the Dennis rear. We will be testing them soon so i will let you know how we get on. Much cheaper than the runner ones, asuming they dont fall apart after a couple of miles that is. Quote Link to comment Share on other sites More sharing options...
8_10 Brass Cleaner Posted April 6, 2011 Share Posted April 6, 2011 We have polyurethane 'rubbers' on the front of my steam tractor. They are rings cut, opened out and bolted on as opposed to pressed on. They do not grip as well as rubber, and are harder, but they do the job. After 20years exposure to oil etc they have started to perish on the side surfaces. Still they'll do a few years yet. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.