Am looking at fitting some more off road focused rubber to my ten, probably the Trelleborg Swiss Army Tyres http://www.trelleborgtyres.co.uk/product_details_32.htm

Only problem is that this site lists the rear as 4.75 * 17 as opposed to 130/80/17 - By my reckoning the 130/80 metric should equate to 5 in inches so the listed tyre (the only 17" listed) is a bit smaller than it should be. Is this a problem or should I just bang on the 4.75 * 17 and be done with it?