the rear tyre size is 4.00*18 , pirelli don't make the MT21 in this size now .has anyone fitted a 110 or will a120metric equivalent fit?how many miles will these tyres last ? on/off road.
thanks for any help
bryan

All I can comment about is the wear resistance. On of the large US mags just tested a new 650GS dakar with the MT21s and reported 4000 miles. This is similar to the 5500 KMs I got from a MT70 on my G/S, fully loaded with about 20% non-paved usage.

I've got a pair of MT21's on my KLR650. They handle great both on (for a knobbie) and offroad. I've got about 2000 miles on the rear one and it looks like i might get another 1000 before it'll need replacement. I did a lot of pavement on them while fully loaded though. They are also kind of expensive.

Kurt

Tires are a compromise no matter how you look at it. The usual factors of grip/ performance vs longevity are compounded even more in dual purpose tires, which have the added complexity of off road grip and puncture resistance. In reality, pulling all these factors together into the perfect tire is not possible. Ask yourself these questions: Am I planning to carry spares or buy on the way? Is it possible to switch between road and off road tires for different legs of the journey (is it worth riding a nobby for 5000 KM so that you can do a better speed on the 300 km dirt section you have planned?)?

If you are truely going back and forth between differnt conditions then you need to prioratize your needs and be clear about what compromises you can live with. There will be a compromise, even if it is mainly in longevity. Be real about the off road capabilities of your bike as well. fitting full nobbies on a 500 pound mostly-road-bike loaded with gear will insure poor tarmac grip and/ or low tire life. On the other hand, you may need the grip to get the beast through that 100 km of mud/ sand/ rock in the middle of your trip!

If it is possible to switch tires, there are cheaper alternatives to the MT21 that might be just fine for an off road section, and can be taken off when you are on better terrain.

I have noticed that the Avon Gripster is a popular choice as a 'compromise' tire for RTW.

hi bryan,

120/80*18 is exactly the same as 4.00*18 (and 110/90*19 is the same as 3.25*19). there are no fitting problems. for the 80's bmw (and newer) you can change this also in your papers - if necessary (in germany we have a lot of regulations about that). just contact your bmw dealer or email to bmw in munich.

look also at "tourenfahrer"-magazin (partner of hu), they tested 7 tires for gs and such kind of bikes in issue 11/2001. if you like i can send you a pdf of the article (in german).

i'm riding a "metzler enduro 4" (120/80) on 860 cc gs-like self-made bmw and had a lot of fun on moody forest tracks AND on well maintained mountain roads. it's now 3,500 km and still looking like new. the last "metzler enduro 3" (4.00) made it for 11,500 km, with a lot of fast highway riding.

long may you run
gerd