WD40 is NOT a lubricant and does not do a very good job when used for that purpose. Check your wheel for wear. If the hole is quite worn, get a piece of brass tubing that will fit over the landing gear axel and then ream out the wheel so you can epoxy in a piece of the tubing to make a new brass bearing for your wheel, it will be better than when new. Just about any type of oil will be much better than WD40.