tire size change

Could I put a 120/60/17 on the front and a 190/50/17 on the rear. I having trouble finding Metzler Z8's in the usual OEM sizes. Also does anyone know what makes a tire model specific. The NC 700 takes 120/70/17 E and I'm wondering what makes it model specific when many other bikes take that same size. Don't really know what the E stands for and there is another tire 120/70/17 M. I don't know what the M stands for either

 

Bladrnr, just curious about the Metzler z8's. Are those what you are currently running on your bike and you would like to stick with them, or would these be a possible upgrade? I don't know specific Metzler model tires, just my 07 had Metzlers fitted when I purchased in Dec 2011. Probably stock with 6,200 Mi. Just replaced at 10,200 with Michelin PR3's and wow feels like a different bike(in a good way). Would highly recommend.
John
P.S. been to Santa Rosa once for my cousins wedding, beautiful area.

 

Theory says you can put any tire you want on your bike as long as it fits on the rim and on the bike, but you can/will change the riding characteristics and in some cases for the worse. If you plan on keeping the tires on for a long time, I would get the stock sizes, if you want to "experiment" then feel free to try a different size, but don't expect your bike to handle the same. As far as what the alpha characters mean, most tire manufacturer websites have a section on how to read the side wall info or at least a FAQ.

Where do you usually shop for tires? locally or online?

 

I'm currently running Z6's and have always run metzlers and would like to stick with them. I prefer to shop locally because I like to support the local economy even if it costs a little more. There really aren't many bike shops around my area anymore because many of them have gone out of business. I have looked online and most places don't have the OEM sizes either. Maybe it's because a new model is coming out and they want to get of back stock. Thanks for the info and I was considering the PR3's if I can't find what I'm looking for.