Will WD40 damage tyres?

Q. My son can be a bit like Frank Spencer sometimes. When cleaning his chain he often gets WD40 all over his rear tyre, too.

Despite me warning him not to, he declares: “It’s OK, I clean it off afterwards!” Does it damage the rubber compound itself or not?
Joe Perkins, London

A. WD40 is a water dispersant, not a lubricant, so he should not be using that on his chain anyway. If he wipes off the overspray immediately it shouldn’t do any harm, but leave it on there for more than a few minutes and it will soak in, and it could compromise the grip at maximum lean where he most needs it most.

To clean the chain he should use paraffin and a paintbrush, then lube it. The best time to do this is AFTER a run, as the chain will be warm, easier to clean, and better at taking up the fresh lube.