I change flat tires a LOT, i got 6 last year alone! Once I realized I had a flat when I was at a rest area, and pulled over to an empty part of the lot, so as to not get run over, and unpacked the back of my car to get at the spare (had just left my mom's house, and she's a shopper!), and started changing the tire... there was a 40ish guy leaning on his car, right next to me, smoking a cigarette... he watched, intently, until I was tightening the lug nuts on the new tire, and then said "hey, you need a hand?" I was SO annoyed! Just sit there gawking until I'm practically done? I coolly told him that 'thanks anyway, I've pretty much got it under control by now.' I really believe that able bodied men should ask if they can help from the get go... though I would certainly decline anyway, since I am fully capable, but it's just polite to offer!