I have 70,000 mi. on my Honda CRV and am about ready for replacement tires.I would to purchase the highly rated Michelin
Cross Terrain SUV but they aren't available in my size which
is 205/70-R15. The closest size available is 225/70-R15.I called around to different dealers for their opinions and some say it's OK to use another size and some don't.I also emailed Michelin who said they
don't recommend it saying 225/70 have a different circumfrence and
width.I thought 225/70 were just a little wider and would like to know
whether I can go with the larger size.
Thanks

The 225/70-15 with an overall diameter of 27.5" is 1.2" taller than your OE tire and would hurt the acceleration of the CRV but, would fit.

A very good tire size calculator is at the site below. It gives a graphic representation of a new tire vs the original one you are comparing it to. At the bottom of the page, you can compare tires of different sizes and it will tell you how much each differs from the original. It gives all the tire dimensions, revs/mile, and % change from the original. A very helpful site.

http://www.miata.net/garage/tirecalc.html