an easier option would be to get a sheet of plywood and put it up against the tyres and tilt it until the blob touches it. Obviously it won't be 100% accurate as your suspension would be compressing and tryes deforming if you were actually cranked over far enough to ground out the peg on the go but it would give you an indication of where it would strike. TBH though, all the pegs I've seen with scratches on the blobs had them a lot lower and looked a lot rougher so it having been scraped against something when moving it around is far more likely to be the cause of this IMO