MTFCA Forum

It was to accommodate balloon tyres which ran at lower pressures and gave a more comfortable ride. The beads were wire reinforced so would not stretch lke BE Ttyres used previously. To be able to fit them the rims either had to be split so they could be contracted to go inside the tyre, or the rims had to have a removable lock ring which was fitted after the tyre was put on the rim. Split rims were soon deleted in favour of rims with a drop centre like the 26-7 T wire wheels.
Heavy vehicles still used lockring type rims well into the 1970's and later, prior to tubeless tyres for drop centre rims on those too.
Allan from down under.

I share the same question. Could someone help me understand why, if a 21 inch balloon tire could
be mounted on a 26/7 wire wheel rim, it could not be mounted on
a one piece 21 inch demountable rim? Is it the drop center?
If so. would it have been easier to build one piece drop center demountable rims?
Yes the wood wheels would to have a smaller diameter to accommodate the drop center,
but this could be part of the update to the improved automobile.
The design seems to have been a poor solution.
Harry Lillo
Calgary

The other option is “lock ring” style rims where one side removes. Sometimes the ring has a cut in it and sometimes there is a third locking ring. This design was used on big trucks into the’60’s and perhaps later. 3/4 and 1 ton trucks with 16” and bigger rims also used this design.

Harry L
"I share the same question. Could someone help me understand why, if a 21 inch balloon tire could
be mounted on a 26/7 wire wheel rim, it could not be mounted on
a one piece 21 inch demountable rim? Is it the drop center?"

[Yes, its the drop center. As allen explained, the tire beads wont stretch requiring a drop center to , essentially make the rim smaller by slipping one side of the bead in the drop part of the rim. A split rim actually is physically made smaller by collapsing.]

"If so. would it have been easier to build one piece drop center demountable rims?"

[Later artillery wheels are made this way with a drop center, but still wood spokes. I am familiar with 33 dodge wheels, but many makes used them in the early 30's. then the wood spoke concept was dropped for all steel wheels.]

"Yes the wood wheels would to have a smaller diameter to accommodate the drop center,"

[Yes, they are/were.]

On a related note, I have a set of 30 x 3.5" beaded tires bought by mistake.(non clincher)
They require a lock ring wheel or a split rim. One of the local T ladies owns a T with 30 x 3.5" split rims. Word has it, they were/are popular in Argentina. I have not seen another set or loose single in the states.

I have split rims and straight sided balloon tyres on my 24 Tarrant tourer. Part of the Tarrant special specificatoion was the use of 4.40 x 23* BE tyres, but these are no longer made. My 4.40 x 23" straight sided tyres are on Chev split rims, with the valve stem hole shifted. When they wear out I will revert to Blockley BE tyres.

Allan from down under.

For Harry,
The split rim was in use by others when Ford introduced them on the 26 T's, so they were following the herd. Ford took a lead on them when he introduced the drop centre rim on the T wire wheels, and he stayed ahead while the others all caught up. Devising a way to mount drop centre rims on wooden wheels would have been made a redundant step very quickly.
Others have mentioned the continued use of lock ring type wheels on heavy vehicles. Because of the loads they have to carry, these tyres are very substantially built, making them impossible to mount on drop centre rims. On these the tyre and tube are assembled as a unit, with the obligatory flap, and dropped onto the rim. Then the lockrings are fitted, and the tyre/rim assembly put in a cage before airing up. They have been known to explode the lockring off the rim, with devastating effect for the operator.
Later radial tyres for trucks allowed for their mounting on drop centre rims.

Allan from down under.