Tire sizes

[Jim Grammer <jimg@domain.elided>]

Well, I'm definitely not a tire expert.

I'll admit that in my rush to obsolete the old bias ply tire sizes I 
painted with a bit too broad a brush. The whole subject's kinda confusing 
for most folks, so I was eager to simplify(i.e. no discussion of metric 
sizing, aspect ratio, etc) and left out the radials that are available in 
*x* sizes. The average tire buyer these days isn't gonna see 'em unless 
they go snooping around commercial vehicles or have a dually pickup. I 
checked out some 7.50xR17's when I was thinking about buying an A-120 4x4 
Travelall.

So, in my defense, I 'meant' that the designations were obsolete for bias 
ply tires, but didn't bother to say that something very similar(add the R 
before the wheel diameter)was available in radials. While we're at it, it 
appears that bias ply's may be alive and well if you live in farm 
country(I've seen reference to F&F before as a source). They have been out 
of circulation in CA for awhile now(collector and off road tires excepted).

I'm not sure about the recap situation. I suspect that recaps work best 
where the tire is designed with a big, buttressed tread platform that 
resists tread/casing squirm. A 'caps biggest enemy has to be heat from the 
tread moving around on the casing trying to rip the vulcanize apart. 
Recapping seems to have a pretty good track record for over the road 
trucks, and their tires are designed that way.

If you're wanting to swap around wheel sizes, it probably bears repeating 
that the wheel sizes that end in '.5'(i.e.16.5, 17.5) do not have the 
'safety bead' that is more likely to retain the bead on it's seat during a 
deflation.

Jim