Front tire "cupping" & tire date

[BareKat]

Over the winter I plan to p/u some tires... the back because of the flat bald spot and the front because it appears to be cupping between the tread blocks.

I ususally have the front preload at the 3rd position for quicker turn-in but during a 3600km trip this summer I went to the lowest setting for comfort.

What is the cause of tire cupping (both sides of the tire)... I occasionally ride aggressively and I didn't know if the cupping was normal wear.

tx LBJGH

[Black_peter]

Tire pressure is the leading reason for cupping. It's caused by heat.

[AKA AllyKat]

From what I've read its from tire air pressure But I checked and maintained mine every couple days (Never of by one or two lbs of air) and it was starting to cup. It was a Dunlop with about 14000 miles on it.

[GytRDunKat]

Tire pressure is the leading reason for cupping. It's caused by heat.

+1

[md86]

And Kats don't have preload adjustment on the forks . That's damping .

[BareKat]

K thanks ... preload.

Heat eh? hmm, I usually ride with 2-up tire pressure as I'm larger than average.

[md86]

Some tires , just by their design , seem more prone to cuppage then others , too .

[elkat]

Tire cupping is a little tire pressure, and a lot of not being able to rotate. If you leave a car tire on one spot, it will also start to cup like that. Just happens quicker on a motorcycle tire as even the good ones can't go 40K.

[slick1]

Pressure.

[The CyberPoet]

Tire Pressure and heat are inter-related. If the tire is low on pressure, the contact spot deforms the tire more each rotation, meaning the tire builds more heat with each pass. Since heat is the method by which the component molecules are bonded together when they make the tire, it only follows that as the same rubber gets too hot, it comes unglued and wears at an accelerated rate.

Tire cupping at the left & right edges of the tire can also indicate a rider who pushes the tires pretty hard while leaned over, such as often changing course repeatedly during a banked-over turn.

Some brands and makes are more susceptible to it than others because of how they deal with heat and how they dissipate heat.

Still, you can't go wrong keeping the tire pressures set correctly -- it'll help minimize cupping and maximize mileage out of a set of tires. And keeping the pressure correct means checking it every few days (if you ride once a week, they should be checked/topped off each time you ride).

Cheers,
=-= The CyberPoet

[suzuki2000]

my front tire seems to be doing the same.

If it starts cupping, can you stop it?
Is there an acceptable amount of cupping?

Before I parked my bike for the winter, riding, there was no difference it the way it rode, but when does it become unacceptable or dangerous?

I am a fairly new rider, so my questions may be dumb but certainly better asked then not

[GytRDunKat]

my front tire seems to be doing the same.

If it starts cupping, can you stop it?
Is there an acceptable amount of cupping?

Before I parked my bike for the winter, riding, there was no difference it the way it rode, but when does it become unacceptable or dangerous?

I am a fairly new rider, so my questions may be dumb but certainly better asked then not

Cupping is mostly related to air pressure, as stated.... Do you have Dunlops (most common)? If your new to riding, it can seriously deminish your enjoyment (or not increase the enjoyment). If you've never felt the difference, get a new set of rubber... It's night and day. Cupping can cause all kinds of issues that a new rider will not be able to tell. My next door neighbor was ready to sell his FZR600 because it felt terrible, which later on, I tried, and knew what he was talking about. On a ride, he took my Kat and was totally impressed, actually had a smile, which made me feel good. The next stop I wanted my bike back, because I felt completely unsafe driving that bike. It's like it had harley tires on it (square profile). Because of his inexperience, he rode the Kat, I took the fizzer back very slow, only because I didn't feel safe with him riding it. Once it had new tires, I gave him the keys back. This made a bit of a ripple with his wife (which turned out to be a good thing), who is good friends with my wife. Once explained, all was good.

He hasn't sold the bike now that he can actually enjoy the bike and he took it off the market.

I felt absolutely terrible that his first experience (read - first 6 mos, before I took a chance on it) was on such a ill-handling machine that had such crappy tires on it. Thank goodness he has new rubber (conti's I think), I almost lost a riding partner because of it, in every sense of the meaning.

[The CyberPoet]

If it starts cupping, can you stop it?
Is there an acceptable amount of cupping?

Depends on the tire brand and how much tread-wear you already have. I've seen cases of very early cupping due to running the pressure too low on tires with a lot of tread left (a specific set of Malloc's Z6 tires running at 26 psi come to mind) -- increasing the tire pressure to what it should have been and staying on top of checking the pressures wore the tires even again in about 400 hundred miles. But that's the exception to the rule; usually once cupped, the tire is already too worn to have the cupping wear away again.

Cupping happens because of a localized heat build-up that isn't spreading across the tire properly because the heat is building up far too fast, and that in turn is almost always down the tire deforming at the contact patch more than it should. And the size of the deformation area relates directly to the tire pressure compared to the weight of the bike+load. How hot the pavement is and how far you travel both factor in as well (hotter ground heats tires more; longer journeys run tires hotter).
Ideal tire pressures are commonly expressed for a 140 lb rider without any cargo, riding solo. Thus, if you clock in at 185 lbs, carry a 20 lb backpack, you're at least a couple PSI down from where you should be to maintain the same contact-patch size (and deflection amount) at the tire/ground interface.

Motorcycle tires have a lot of surface area compared to their volume (at least compared to most car tires); the result is that they lose pressure through their carcasses much faster than cars and need to have the tire pressure checked & adjusted far more often to remain safe. Personally, i advocate checking them at least once a week, plus any time the ambient temp changes by 10 degrees or more. Myself, I regularly check my tires before I set out for the first ride of the day; the use of a footpump with an integrated gauge means it takes virtually no extra effort for me to add a couple lbs over simply measuring the tire.

Cheers,
=-= The CyberPoet

[Fox Fader]

It's all about the tire design. My stockers have done the same thing, the stockers on my Bandit did too and I ALWAYS keep my psi proper.

The tires I used on my car have started to do this. I ran the stockers all the way out and they didn't.