safely narrowing a set of wheels?

[Denny]

Cutting and welding alloy wheels can be accomplished safely ...but you better be damn sure of the welding skills of the person doing the work.

I wouldn't trust such an extreme operation to anyone, except to an absolute expert in welding alloy materials. Someone welding in the aircraft manufacturing industry would be a good candidate. Alloy welding requires unique skills and a thorough understanding of metallurgy. I've seen the process performed first hand and the guy doing the welding had the skills of a surgeon. He even x-rayed the welds to check for complete weld penetration and no air-pockets when he was finished just to make sure that the wheels were bullet proof. He wasn't about to let an unsafe job leave his shop. He learned to weld in the Navy where he worked on jet aircraft welding high stress components like land gear and wing ribs. He knew his stuff when it came to welding.

One more thing. Expect to pay a premium price for the work.