Hi there,
OK, I could be talking complete rubbish based on what's now a very hazy memory of metallurgy, so bearing that in mind.....
I think that a lot of alloy wheels were made in LM25 alloy back in the day as it was a very popular casting alloy for sand & gravity castings and also had some resistance to seawater (salted roads ?). Anyway, LM25 comes (came ?) in 3 heat treated forms plus a basic "as cast" structure. I would guess that alloy wheels were "as cast" because with a chunky casting you don't need a massively strong alloy.
But my concern is that it's possible to get precipitation hardened grades through heat treatment, so randomly using heat with Al alloys makes me look twice at what is being done. The chances are with such a bulk of material in a wheel is that nothing significant happens and all is well, but even so I'd want to know the track record/experience of who was doing the work.
First caveat - I don't know for sure that's how Lotus rims were, but a lot of alloy wheels were made that way. Second caveat - I don't know the heat treatment/as cast condition or the experience of where you'll get the work done.
Personally I'd go with John and simply replace the wheel with a known good one. They crop up on a regular basis for not much money so I'd only consider straightening a rim if they were unobtainium.
Brian
