You didn't say what type of vehicle, which could make a significant difference. If its FWD the rear wheels are just along for the ride and there is no real stress. If its RWD you might have some differential components working harder to compensate for the .2" difference. However, it will take a long time for it to cause enough stress to get worried about.
Put the tire replacement on your list of fixes, but its not something that has to be done ASAP unless you have ABS brake sensors or traction control that would be affected and cause a safety issue.