as above i would have thought an enginners certificate would be good knowing its been welded to a high level and not likly to leak. I looked into it a while ago and i believe you used to be able to buy wider rims without centres and have yours placed into them or cut the centres out of a wider wheel of the same diameters and then place your centres inside as in a way thats how wheels are made with the centres welded inside the rim and if this wwas done correctly and all centred and squared up correcty there would be a lot less welding involved.