A Note on Metzler 880 Tire Pressures

There was some discussion at STC on tire pressure. Some people believed that BMW had made a mistake in their published recommended pressure for the K1200LT on Metzler 880's.

My 2005 K1200LT recommends 36 front, and 42 rear (46 rear when 2 up and fully loaded). I did the math, and the kPa actually converts to 36 1/2 front, so I just run 37 front / 43 rear.

People seem to believe (probably because of past years experiences with tire wear and cupping on LT's) that a much higher pressure is called for - even Susan Galpin seemed inclined to agree. At STC, I heard a large group of people say they ran 40 front / 46 (or more) rear. I also heard claims that Metzler recommends much higher pressure than BMW. I looked on the Metzler site, and it turns out to be NOT TRUE. Metzler recommends 36 front / 38 rear:

See page 18 of the Metzler 2005 brochure.

I have over 10,000 miles on my tires, and the wear is quite nice and even (I'd say a little more than 1/2 way - so I might expect 18,000 the way I ride - I should say had been riding). This suggests to me that BMW has roughly correct recommendations (36/42).

On my way back from STC, I didn't up my rear pressure (fully loaded with camping gear, and a week's worth of stuff) and noted the rear felt just a little "swimmy". Second day, the rear was 43 cold. I upped it to 46 and it felt much better at speed, on curves.

I think 2005 and up BMW tire pressure recommendations for K1200LT are reasonable.

• Too little pressure can cause cupping from the effect of the tire contact patch being... well, cupped.
  
• Too much can cause a ballooned / reduced tire patch - something I really notice in the wet (poorer grip).
  

Maybe for track day it's worth upping pressures so you can do nice smooth (and easier) drifting, but for streets, I'll stick w/ BMW recommended pressures - I see them working. I may try Metzler's lower pressure, but have doubts based on how 4 pounds down felt with a fully loaded bike.

I hope this sets straight Metzler's recommendations, and generates some needed discussion.