Thanks Malcolm, from that Range info I found LongStoneTyres.com. From these people i figure the following would be a good combo
275/55/15 rears 10.82" wide, wall height 5.95", Dia 26.91"
225/65/15 fronts 8.86" wide, Wall height 5.76", Dia 26.51
So they should look good together (assuming my maths is right)
Also seems Avon are the only company that do both sizes in the same model tyre.
Only had a brief look on the web so if anybody knows different, please let me know
ANT