Copy-paste-edit from another thread:
These are [url=https://github.com/CleverRaven/Cataclysm-DDA/issues/19863]known[/url], arising from those vehicle parts using "legacy" definitions, which have a fallback in code to minimum difficulty 2. One could port just these two to the newer format, but that's a "special snowflake" approach that could make it harder for someone to tackle the rest later...
I’ve taken the liberty to submit a PR that did this for storage batteries and their cases, seeing how annoying it was, partially contradicting myself - but not too much, since these have already been shuffled into a proper category file.
Wheels have been moved to a proper file, too, so this could be done… But they’re not as straightforward as storage batteries.
From RL, changing an auto wheel does require some “mechanics” knowledge - where to put the jack, how to apply leverage, especially without twisting old bolts off, etc., - but this mustn’t spill over into bicycle/cart wheels… Anyway, this will take a while if it’s to be done once.
