Welding Alloy Wheels?

After working as an alloy wheel design and testing engineer at Performance Wheels, where Dave's wheels probably were produced, I would not even consider welding, and besides, it is illegal in Australia to weld alloy wheels radially (spoked sections), although circumference welding is allowed in some cases (i.e. widening of rim).

The reason they have cracked is due to fatiuge failure, and while the cracks may be small, the material in that area has been affected, and unless the wheel is re-heat treated, then the welding will only cover the cracks, and not add strength to the wheel. (All Aust manufactured wheels must be heat treated , whereas most European alloy wheel standards do not require it).

The fatigue failure occurs through work hardening of the material in areas undergoing stress (think of breaking a piece of wire by bending it, the break area is harder than the rest of the wire), in a wheel this occurs at the join between spoke and rim, or spoke and hub, depending on the weakest point of design, and these are tested for by a radial fatigue test (pressure down on the wheel rim) and cornering fatigue test (pressure on the hub, trying to bend spokes).

The superlite(minilight) design i tested came in many sizes, from 12x5 up to 15x8, and everyone failed under fatigue testing in generally the same area, and the only way to rectify it was to increase the thicknesses of the spokes. i must stress that the testing conditions were very extreme cases, i think design factor was 2.5.

The problem is that any extreme force applied to a wheel in it's life will affect it's fatigue strength, eg hitting a curb, thus reducing the life of a wheel.

The Wheel Industry Association Aust.(WIA), has for many years been trying to prevent the sale of second hand wheels from wreckers, etc, because the history of the wheel is not known, and even go as far to suggest that if a car has been in an accident, all alloy wheels should be replaced, because their future strength may be suspect.