Thanks to everyone who replied to this post.I am leaning toward the 21/18 setup.according to metzeler's website the 120/70-21 me880 is rated at 584# and the 160/60R18 is rated at 882# for a total of 1466#.Total capacity of the stock Dunlops is 1691#.Is 1466# adequate for a Road Glide. I estimate total load at 1329# based on harleys listed wet weight of 789# ,250# rider,140# passenger and 150# for saddlebag and tour pack load.Is this realistic.I cant find the GVWR listed for this bike.Switching to a 140/70-18 raises the rating to 1559#.I ran the 18/18 setup on my 99 FLHT with a 140 rear tire and had no problems except poor wear caused by running Harleys recommended pressure instead of metzelers higher pressures. The bike is ridden 2 up with a chopped tour pack most of the time although not heavily loaded (just day trip items jackets rain suits etc) I have attached a picture of the 99 FLHT .I don't have any of the RG yet but I will as soon as the wheels are on. Thanks for the help. Wayne
When I did my wheels, I was cautioned by Metzler about going to the 160/60 rear tire, if my main use of the bike was for what it was intended...touring. Not that the tire won't work, but because the tire does not have the volume of air necessary to disipate the heat that builds up in the tire when two up, and particularly two up and loaded for a trip. If you use that tire, expect no more than 5k in mileage out of the rear, and it is not an easy tire to find on the road if you have a problem. Certainly, any shop can have one shipped overnight, but expect some down time if you have a flat, or the tire suddenly wears out on you while on a trip...I learned the hard way that once a tire gets to a certain point in it's wear, it goes FAST!!! Also, IMO, you cannot look only at the total load rating for both tires combined...MUCH more of the weight distribution is on the rear tire when you are two up and loaded, so it is the most critical one to look at. 95% of the time, my SEUC is ridden two up, and the vast majority of that time is loaded with several days worth of luggage....for the reasons stated, I chose to go with a 140/90X16 rear and a 140/70X18 front....both Metzlers. I have been very happy with my decision.
If you go with the 21" on front, definitely take measures to clearance the front fender if you use the stock front fender. More than one person has discovered that the hard way too. A 19" front does not give you that problem. Not trying to suggest not doing what you want to do, but I did a LOT of research and calling on this subject, and just offering food for thought.