I think those would form over, rather than into, a form.
I agree with the concensus - something to beat a rim back out against.
Think about how it would be if you hit a curb or a big rock in one of those jalopies.
Chilly
Um Chilly, when is the last time you saw a dented steel tire on a wood wheel? Anything that could dent such a tire would also demolish the wood behind it.
Seems like in the days of steel tires anybody who could afford such a block of iron sitting around would also have owned a tire roller, and probably used the roller to get a tire back into shape while the wood wheel was rebuilt.
The boys in the steel tire business, even the current crowd of Amish Wheelwrights tend to be very savvy about saving labor.
Possibly it's an anvil for welding steel tires, the depression on the right sure looks like somebody worked that area hard and missed the target a number of times as well. The holes could have been for a clamping system making it easier to maintain the tire in position while the striker beat hell out of it.
Trouble is, I can't find it in Blacksmith & Wheelwright.