Rover Sports Register Forum

5.25/5.50 are the nominal widths in inches - the actual width was somewhere in between on this dual size. The aspect ratio (height) is almost 100% on cross plies - radials mostly have less than 80% so are much lower

To clear the terms. height etc have look here (and no Americanism, it is a traditional British terminology):
https://lulis.org/2012/04/19/26-453-%d7 ... %99%d7%92/

Most informative - I do not know what Rover 10 owners do in the UK. The Avon tread pattern was most decorative but not very water dispersant. I have one on a spare wheel but given it must be over 60 years old I do not intend to drive on it!

The Google translator although set for UK English (why should our English require a qualifier?!!) spells TYRES as TIRES

If In understand it right then the Nominal Width refers to the tyre not the wheel. I recal the inside of steel wheels being stamped 4.5J or 5J that being the nominal rim width. the Rover wheels look quite wide, but are probably 4" or so. Anyon gotb s rim without a tyre to have a look or can put a rule across it ?
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Yes the width is the tyre tread - I have an empty wheel and will measure it soon - 4" seems right

Some more information on cross-ply tires. There is a difference between the rim width the the tire diameter. The same rim can support many tire diameters. What is special about the "R" tires is that they retain the same cross section as the "X". See attached pictures.

The rim width at the well is 3½" on our 1939 16 17" wires

It will except both 17X550 and 17R550. BTW, my easy clean 1947 wheels have the same width.

Thanks for that information
The Radials 165 that I located are , I think, going to need too great a rim width:- 4.5" minimum. Confusingly there are tall & narrow 17" radials listed, but they are for use as spare tyres (space saver types!) with no speed nor weight rating! not a good idea I think!!

Air pressure from the tube would force the tyre rim outwards into the sides of the wheel bead but whether it would stay in contact with the bottom of the bead well in use especially braking and cornering is unknown. The outside width of the wheel is 4½" also.

I think I read somewhere that unrated speed tyres have max of 50 mph so if your car is capable of this speed irrespective as whether it will be driven so fast then it is dangerous and unroadworthy.

As I said before I see no benefit of radials over X plies on P2s certainly unrated speed radial tyres that are too wide cannot be safer than new X plies of the correct size in my view