Originally Posted by mreuter
Ok, you Guy's should know what you are doing. Maybe a mixed pair is good enough for straights and up to 80 mi /h and I know a lot of LT owners do this in the states.
In the German Papers to the Bike it says " Reifenpaar nur von einem Hersteller zulässig" translated "Tires front and rear are only of one manufacturer permitted".
If Police stops me with a mixed pair of tires over here they take the bike of the road.
Once again please don't take it as a criticism from my side on that what you are doing, just wonna let you know it is not safe even if you mean that.
There change also 100 k mi not my mind, sorry.
I think you are confusing "known to be safe" and "known to be unsafe" with "safe" and "unsafe."
Manufacturer's include statements like the one you reference due to the fact that they simply don't have the resources to rest all possible combinations of tires and such that owner's may choose to install on their bikes. So, they test one combination thoroughly and then approve that combination as being safe. This does NOT mean that other combinations are not safe, it just means that no testing has been done and thus it is not known if they are safe or not safe.
Unless you have tested another combination of tires and have data that suggests that combination is somehow unsafe, you can't proclaim it unsafe simply because it is not the safe combination the manufacturer specifies.
There is a similar issue in the aviation world. Most certified airplanes have a specification called the "maximum demonstrated crosswind." This is required by the FAA to be at least 0.2 x Vso (twice the power-off stall speed). The manufacturer has to list this speed and it must meet the FAA minimum, however, the actual cross wind component that a given airplane can handle may be much higher than either the FAA minimum or the value "demonstrated" during flight tests. The demonstrated value is simply the capability that the manufacturer had the time and resources to demonstrate. It may be that they simple didn't have time to keep testing until they found the ultimate limiting wind speed.
So, if you attempt to land in a cross wind greater than the demonstrated amount, you are now a test pilot. You may well be successful, but you are operating in a regime that the airplane has not tested. Same with mixing tire brands. Any given combination may well be very safe and perform very well, but you are now a test rider for BMW as you are exploring an area they likely did not explore.