advice on rear tire

hope this doesn't get too confusing. i bought 2 new 19" avons for the '72 i'm trying to get going. today i discovered the rear is an 18" wheel when i began to take it off. doh!!!!!!!!!!!! the front will be an avon am26 100-90v-19. need advice for the 18" rear. i know they came standard w/19" wheels. somewhere along the line it was switched. wheels look identical. did any nortons come w/ 18" rears? anyhoo i need to return the tire for an 18" and need reccommendations as to what size. i'm a new rider and put a premium on handling/stability. what's the upshot on running 18" rears and 19" front? thanx, rick
'

18" rear is a common change for a lot of brit bikes. I prefer 19" myself, but many here run 18. Do a tire search to find the preferred size. I would imagine a 100 or 110 - 18 in the same Avon as the front, but have no personal experience.

19" is the correct size, But many have laced up 18" rear rims for alittle wider choice of tires. I put a 18" rear on my Commando for that very reason. I currently have Michelin McAdams on the machine now, a 325/19 ft, 400/18 rear. I went through a set of Bridgestone BT45's as well 100/90x19 ft 110/90x18 rear. Both sets of tires have worked well. I think a 120 is alittle too big for the rear, but I have seen them installed.

Ken G.

thanks boys, rick

Rick
Many folk put a 18" on the rear, I have.
The standard setup was 19" WM2 rims with 100/90/19 tires.
If you put an 18" on the rear it is normally a WM3 rim, so you can put a slightly wider tyre on.
As you put a wider tyre on it will be taller, So you get back to the original diameter you would have had from a stock 19" setup.

I run a 110/90/18 Avon roadrider on the rear and a 100/80/19 on the front. I would recommend this choise, especially if you have a wider rim on the rear than on the front, not the thinner 100/90/18.

Mat Rambow uses 120/90/18 tyres on some bikes, on a WM4 rim. This I believe is the widest tyre you can fit into a Commando without fouling...but don't put one on a WM2 rim, or you will have handling problems.

Stu.