CVO Technical > Wheels/Tires/Suspension/Brakes
Metzeler 888 Pressures
efrbc1:
Have had a set of ME 888's on my '05 Cherry for about 11K. Rear is worn and needs to be replaced. Usually get double the life out of the fronts (880's) but this front tire has started to cup and will be replaced also. Have been running them at the same pressures as I did for the 880's (46 rear and 43 front). Spoke with a rep from Metzeler today and he recommended (per their specs) running the rear at 38-40 and the front at 36-40 both of which are lower than the 880 recommendations. Checked the tires and they both have 40 PSI as the max pressure marked on them.
Any thoughts out there as to my "overpressure" in the front being the cause of the cupping?
The Metzeler rep is sending me the spec sheets for the 888 tire with load ratings, pressures etc. Looks like I'll be running them at lower pressures from now on.......
Chris
twinotter:
I'd run the max stated on the tire. Cupping front tires is usally caused by unwanted flex (scwirming) of the tread. Underinflation is a prime reason for cupping, and on some extra hard braking can do the same even on a properly inflated tire, but especially on one even a couple of lbs low.
I ruined a brand new Dunlop 591 front with two hard stops from 130 mph, the tire kind shredded in certain zones and hummed like the devil. I found it was at 28lbs instead of 30!!
I now check pressures COLD once a week, can't afford to give $$ away needlessly. twinotter
efrbc1:
Got the printed material from Metzeler and they call for 36-40 for an MT90-16 Front ME888. I had been running at 42-43. Wouldn't think that 2-3 lbs over would cause cupping but I'll be running 40 in the new one.
Chris
mark:
I think some motorcycle tires are just prone to cupping. I check my air pressure religiously and my last set cupped after they were about 3/4 worn.
ric.sut32@gmail.com:
I joined this site just to set the records straight on tire pressure. As a tire designer of 42 plus years. The statement "set your pressure to the max on the tire" is wrong!!!. The max pressure on the tire sidewall is exactly that. It is the maximum pressure the tire can be safely inflated. The inflation pressure of a tire is dependent on load. For cars this inflation pressure is usually on the driver’s side door jam. Bikes on a frame sticker. This is the cold inflation pressure which means the tire has not been run to generate any additional heat from flexing. If you must add air in a hot tire situation it is recommended to add 4 PSI to the sticker pressure and recheck/adjust after a cooling period like overnight. Pressure recommendations also need to be adjusted for signigantly elevations above sea level and that data is on the net. This is THE answer as it follows the laws of physics and last time I checked gravity was pretty much the same and fairly stable. Now as a designer/test driver/and racer I do reduce pressures to increase contact patch size as desired. This does increase sidewall flexing and heat generation which increases wear and tire life. (FYI cupping is usually balance and sometimes suspension issues. Poor dynamic balancing accentuates harmonics which increases bounce. I always Road Force / match mount balance my cars. )
I never go lower than 4 psi but again I am taking my own liberties and risk doing so. As a designer I cannot recommend anything different from manufactures specifications as that is what the vehicle passed DOT safety requirements with for highway approval... and my legal staff would have heart failure. I will say that modern vehicles air pressures and getting higher and this is related to noise and rolling resistance goals. Harder tires have smaller contact patches resulting in less fictional loses, less noise and increased gas mileage from lower rolling resistance.
For me the ride on the bike is far more important than the tire mileage so I play with lower air pressures and only use high performance top end tires that are VERY durable. Have fun, be safe and enjoy!
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