There are two types of TRC (PCC) wheels, standard resilient and super resilient. With both, the axle has a cheek plate slightly smaller than the inner diameter of the tread, and the wheel --it's true wheel, not a tire-- is fastened to this plate using various bolting arrangements with rubber sandwiches on either side of the wheel's plate (which is part of the wheel, not the cheek plate on the axle). The standard resilient has a large nut on the center of the end of the axle, and the rubbler sandwich and wheel must be assembled with a portable hydraulic press. The super resilient wheel is the one with the concentric circles of smaller bolts and nuts, has thicker rubber sandwiches, and can be assembled with a wrench (usually and impact wrench). Electrical connection between the wheel and the cheekplate (and carbody) is made with copper shunts, which have taper pins on the ends so they can be driven in with a hammer and punch. ISTR that because of the difference in the thickness of the rubber sandwiches (super are thicker), you have to modify the axle (positioning of the cheekplate) to convert standard to super or vice versa.

The 1040 in SF was outfitted with Bochum wheels 25 odd years ago. These are a resilient wheel, but unlike the TRC wheels, which are true wheels with wheel plates, Bochum wheels are merely a tire pressed over a set of rubber blocks arranged around a hub. They don't use the copper shunts, because electrical connection is made with about 4 special rubber blocks which have a copper cable in the center which presses against the outer surface of the hub and the inside surface of the tire.

TRC wheels can be taken off and serviced --true the treads on a lathe, which you don't want to do with the wheel mounted on the cheekplate-- and put back on, but with Bochum wheels, you have to cut the tire to get it off (and then throw the tire away).

Bochum wheels are much more noisy than super resient ones.

In the 1960s, the MBTA started using solid wheels as a cost cutting measure. The cars always felt like they were running on sandy, gravel covered track, and the equalizing levers on the B-2 trucks started breaking. Any Boston PCC truck without Clark stamped on the equalizing bar has had this problem because the replacements were made from plain, unadorned flat steel plate.