Will there be a significant difference in the tread life of a 16" vs. a 18" tire?

I'm thinking of getting custom wheels, but I ride daily to work and put about 70 miles a day on the bike. I think the 18's look better since they show more wheel, but I don't want to be buying tires every few months.

Thanks

 

I have been running 18" Akront spoked rims on my 03 Roadking for over 70K miles and still going, the tires wear at the same rate as 16" about 10 to 12 K miles for rear and twice that for front.
The bike will ride stiffer due to no sidewall flex. 18" tire choices are limited, for my size I can go with Avon or Metzlers, I had trouble with Avons years ago on my Shovelhead so that leaves me with Metzlers. Shop around on who you buy them from, I found that the cheapest I can get a rear tire for is about $180 plus 15 for the tube, 6 for the rim liner and another 35 for mount and balance. The Dealer near me happens to be the cheapest, going through JP cycles or other on lines are more expensive, go figure.
I plan on staying with 16" on my Streetglide for three reasons, they ride better, they cost less and they are always in stock, I have had to order 18" tires before, only a couple days wait but if your on a road trip you don't want to be sitting somewhere waiting for a tire..

 

I hadn't thought of this before, but it makes sense that an 18" should give slightly better mileage, other things being equal. An 18" is going to go around slightly fewer times to cover the same distance. Be interesting to see the results of some real life controlled study.

 

The outside tire diameter should be almost the same therefore you will have the same revolution with either the 16 or 18. That is simply the wheel diameter not the OD of the tire.

 

I am quite suprised by the lack of tires available in 18". You would think of all the people running them there would be more.