Goodyear Fuel Max and PSI to Max MPG

Inflating with pure nitrogen will only help to mitigate fluctuations in pressure due to temperature changes.

Not sure how great that will be, since you should be measuring/inflating your tires when cold. That way your tire pressure is always the minimum you'd want it to be, and it increases a bit when warmed up.

Nitrogen wouldn't be worth $ to me to use. If a shop offered to do it for free, I'd let them.

 

I think the issue is probably more likely to be the water vapour that's in compressed air but not in N2, as supplied. Dry air would probably be as good if it could be found. Water vapour will change its partial pressure quite a bit between -10C and +10C.