R to X convert, rear tire question

Got me some Warp 9's a couple of months ago, not had the time or money to get new tires for both sets.

Looking to fit Conti Attack SM, standard on front, maybe a little wider on rear. Whats the ideal sizing, standard or a centimeter or two wider?

I've done a search but couldn't find the info needed.

Cheers

The biggest I think you can safely go is 150 rear before it starts rubbing stuff. The stock is a 140. I ran a 150 for my previous set and went back to a 140 for the set I have now. There is not a huge difference in performance in my opinion. The 140 feels like it turns in better, I think it is lighter. Scraping pegs with the 150 and there was still about 1/2 inch of unmarked rubber on the tire. The 140 wears right to the edge, but it could also be a function of the profile.

Most of my miles are commuting, it might be a different story if I did a bunch of track days.

I have a set of Distanzia's on my WRX and the rear is a 150. There's lots of room, but I wouldn't go wider because the bike does not have the power to turn the bigger tires.
The Avon's are 120 front and 150 rear and while I know they are heavier than a street tire, I instantly felt the difference the first day I rode it with the Avon's. They felt much slower (turn in) compared to the stock 110/140's. If staying with a street tire, I'd stick to the stock 110/140 sizes simply because they feel lighter/more nimble...

Cheers lads, just the info I was after