Citroen - prewar Citroen 40cm tyres
Many prewar Citroen models (such as the Citroen Rosalie) were fitted with tyre sizes to fit a 40 centimetre (400mm) "millimetric" wheel rim. This wheel works out larger than a 15 inch and smaller than a 16", being actually 15.75". This was a uniquely French thing, which French manufacturers in particular were encouraged to adopt - I suspect because other tyre manufacturers did not make millimetric sizes due to Michelin having sewn up supply of to the French car makers, so it was an excellent marketing ploy if nothing else. Unfortunately where some Vintage era millimetric sizes are no longer made, owners with cars have to have different sized wheels built for their vehicles.
With a 40cm wheel rim size, the tyre sizes quoted in period for the x40 tyres were 130x40, 140x40, 150x40 and 160x40 but these four tyre sizes supplied today for Classic car owners have been morphed together in two very expensive dual marked 130/140x40 and 150/160x40 tyre sizes. The radial ply 165x400 tyre size is also made for this 40cm wheel rim, a wheel size that first made its appearance in 1938. These were of course all cross ply construction tyres.
Our high quality radial ply Blockley 165R400 tyre is often used as an alternative to these x40 sized tyres, built for the same 40cm (i.e. 400mm) wheel rim. See these tyres for example fitted to the Citroen Rosalie below. And in any case, the 165R400 size was used on the Traction Avant post war, whereas prewar they fitted 165x40. Today these superb radial 165HR400 Blockley tyres will handle far better than the x40 Michelin range of tyres available today, and at a vast saving in cost, because Blockley sells its tyres direct. See full details of this 165HR400 tyre below:
