Believe it or not, even wheels have expiration dates

Wheels allow auto designers to dress up otherwise drab rides, they let engineers experiment with and improve handling, and when done right, they’re adored by consumers from any end of the enthusiast spectrum. Lighter, stronger and prettier, especially in alloy form, wheels can be great — until they expire. Wait. No automaker publishes an expiry date for wheels, do they? Not officially, but potholes and Canadian winters in general take their toll, and sometimes, the evidence isn’t obvious. Finish pitting and peeling is the first sign of alloy wheel degradation. Many may think this is only a cosmetic problem, but when the clear coat’s finish surface is broken, it will allow the metal to corrode quicker. This is the main cause of porosity, where air leaks out slowly through hard-to-pinpoint areas. These leaks can also be slow enough so as not to reveal themselves with a standard soapy water test. However, peeling finish on an alloy wheel is no reason on its own to scrap it — there are plenty of shops that specialize in refinishing and repair, with pricing at a fraction of what replacement would cost. Loss of material from corrosion is an issue that usually remains hidden until the rim is removed. After about four or five years of exposure, alloy (and even steel) wheels should be checked for this, especially where the wheel itself mates to the vehicle’s hub. This is a critical area because the weight of the vehicle is supported here by a small ledge of metal on the hubs. When enough metal is lost, this can lead to vibrations, wheel stud stress and even lug nuts coming loose. Nothing can be done to repair this issue. Alloy and steel wheels also share another old-age problem: bead edge leaks. This refers to the edge of the wheel rim that the tire seals against. Moisture gets trapped here due to the condensation that collects during temperature differences between the air inside the wheel and outside. This surface can become rough enough with corrosion to cause slow leaks. Good tire technicians will take the time to grind these areas down to ensure a leak-proof seal when they’re mounting a tire, but even the best don’t always have enough time to do this when tire season is at its peak. And of course, if they don’t dismount a tire, they’ll never see the problem. Bead seal leaks will show up with a soapy water test.