I had what I thought was a puncture until I took the tyre for repair and discovered that the alloy had a hole in it. I must have got a stone stuck on the inside of the wheel and this has punctured the wheel( I had problems reversing immediately before the puncture , the car wouldn't move backwards but went forward okay ). The guy at the tyre shop said that I might be able to get the wheel welded. Anyone had experience of this ? Thanks. David
Alloy Wheel Refurbishment & Uks No. 1 Structural Alloy Wheel Repair Specialist is one of many companies out there (picked from google) and there are vids on YouTube from variouse showing repairs to even massively cracked wheels , other option is look at it as a reason to upgrade your wheel package 
You will pay more to get a wheel welded than its worth there are hundreds of them in the breakers or on ebay get a second hand wheel a welded wheel will always be a welded wheel
