The split rims are split just like cutting a bagel in half - lots of
bolts hold the halves together. back in the olden days a split rim was
a diiferent design -just a slice across the rim itself. A lever locked
the thing in place. Unlocking the lever and lots of muscle allowed you
to overlap the ends and with more muscle and 2 tire irons get the tire
itself off, tube patched, and everything back together. An hour was
about right for the job.
Now the aircraft wheels use facing halves and a big o-ring for a
sealer between the halves. The tires are tubelss, and usually 24 ply.
They can be recapped as many times as the carcass passes inspection.
Some airlines did have limits , but others went 'on condition'. The
wheels are built up, pressurized with N2, and elak-checked fro 24
hours before being released for service. On being delivered to a
aircraft, they are topped off with N2 as required. Herby lies a tale:
I was at Air Florida at Miami when one of our troops took a main mount
wheel out to a 737. It gauged a trifle low so he screwed an N2 line on
the Schrader valve and cranked open the service valve. The line gauge
didn't rise any so he screwed down the pressure regulator a trifle,
Still no rise so he screwed it down some more - and more. An odd sound
hit his ears, sort of a creaking noise. He looked at the wheel just in
time to see the bolts being pulled down through the nuts - he said he
had time to think "now that's strange!" when Whammo the top half of
the wheel took off, his ears were ringing, and talcum powder was
fogging the inside of the van. The wheel half went out through the
roof of the van (sheet metal!), sailed clear over the concourse, and
landed on the other side with a clangor, fortunately missing
everything over there. The service line gauge was broken - it always
read zero despite whatever the line pressure was . . .
FWIW airing up a tire is hazardous - cages are used in tire shops, and
with hot brakes it is very dangerous to get in line with the axle
until everything has cooled off. On a jet, one engine on up, the main
wheel tires take about 30 minutes after landing to reach peak temp.
Some places had the aircraft taxi over spikes to defkate the tires
after a hot landing. Airliners incorporate fuse plugs of low-melting
alloy to relieve pressures and you always hope they will work.
Walt BJ