Cupping

snbusa

Registered
My front tire has plenty of meat on it but is cupping. I was told if I reduce the air pressure from 42 to 40 or 38 the tire would round out and run more evenly. Anyone had this problem and will this work? Thanks!
 

GsxrBots

Motorboatin' Moonpies, Gangnam Style
Registered
I'd replace it, but that's just me. Usually I was under the understanding that under-inflating causes the cupping. Different brand tires are worse than others.
My stock Bridgestone was cupped at like 3000 miles.
 
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GsxrBots

Motorboatin' Moonpies, Gangnam Style
Registered
I've had several tires over the years, and the worst for cupping were always Dunlops. Not sure why.
 

skydivr

Jumps from perfectly good Airplanes
Donating Member
Mine cup also. if you got 3K on it that's not too bad; I'd replace it once it gets bad enough.
 

snbusa

Registered
Its not that bad yet. I think I'm going to inflate to 42 (it was at 40 when I checked it and had gone down to 34 a few weeks ago...no sign of puncture) and run it a little going easy and then replace.
 

snbusa

Registered
Dunlop says to maintain pressure and avoid hard braking...which I do a lot of but won't now. Thanks for leading me to this answer. I was about to do the wrong thing.
 

The Gribbler

Registered
In my opinion dropping the pressure makes the bike a little bit more predictable as you lean if the tires are already cupped, but it will contribute to it cupping worse just along a different path around the tire. I went down to the dragons tail a few weekends ago with cupped tires. We ran the cherohala skyway (higher speed sweeping turns) first, and low and behold the long sustained periods of time where I was leaned over on the cupped part of the tires made the cupped ridge go away. I don't know if this is typical but thats how it went for me.
 

sixpack577

Top Gun
Registered
42psi is way too much, especially for hard cornering.
34 to 36psi cold.
Set the suspension sag for your body weight.
 

IG.

Registered
42 is way too high for the front. Contact patch is very small, effectively wearing off the center of the tire. Lower pressure would create a larger contact patch - thus spreading the weight over a larger area, wearing it off at a slower rate, and more evenly. I use 36-37 rear, 34-35 front for the street during warm season, and 2-3 psi less during the cold season. I like to keep the front 1-2 psi lower than the rear to make sure the front has more traction than the rear at any time. If the rear steps out it's not a big deal. However, the front stepping out is more dangerous.

If I wanted to try to fix a cupped front, I'd drop the pressure to 32-34 psi, and take a lot of turns without accelerating through the turn - either steady on the gas, or very slowly rolling off the throttle. This will ensure good load on the front, but without overloading it. I would avoid taking the turn with the throttle completely closed unless road conditions are perfect.
 

Tufbusa

Track Coach / TufPoodle Coach
Registered
42 is way too high for the front. Contact patch is very small, effectively wearing off the center of the tire. Lower pressure would create a larger contact patch - thus spreading the weight over a larger area, wearing it off at a slower rate, and more evenly. I use 36-37 rear, 34-35 front for the street during warm season, and 2-3 psi less during the cold season. I like to keep the front 1-2 psi lower than the rear to make sure the front has more traction than the rear at any time. If the rear steps out it's not a big deal. However, the front stepping out is more dangerous.

If I wanted to try to fix a cupped front, I'd drop the pressure to 32-34 psi, and take a lot of turns without accelerating through the turn - either steady on the gas, or very slowly rolling off the throttle. This will ensure good load on the front, but without overloading it. I would avoid taking the turn with the throttle completely closed unless road conditions are perfect.

You are a bit confused on how air pressure affects tire ware as well as available traction between front and rear. I've never understood why anyone would choose to run higher pressure in the rear unless it's related to added weight of luggage or passenger. 2-3 pounds less pressure in the front will never equal the traction of the rear since the rear contact patch is almost twice the size of the front. Added tire pressure allows the tire to run cooler thus extending tire life, not reducing it!
 

snbusa

Registered
IG, You're advice to me has always worked out and I'm going to change this tire soon any way...So then, I'm going to try your suggestion and see what comes of it. Thanks a lot to everyone who offered help. It is much appreciated.
 

IG.

Registered
You are a bit confused on how air pressure affects tire ware as well as available traction between front and rear. I've never understood why anyone would choose to run higher pressure in the rear unless it's related to added weight of luggage or passenger. 2-3 pounds less pressure in the front will never equal the traction of the rear since the rear contact patch is almost twice the size of the front. Added tire pressure allows the tire to run cooler thus extending tire life, not reducing it!

Tuff, you are confused. But you are right - I didn't phrase it correctly. I didn't mean the front will literally have more traction. I meant I prefer to shift the bias in favor of the front having more traction that it would with higher pressure. Of all the people, you should know what I meant. So, once again - not bumping the rear pressure, but dropping the pressure on the front a bit.

And having high pressure on the front will eat the middle of the tire at the higher rate because the same weight is sitting on the contact patch of the smaller size. And yes, the tire will run cooler with higher pressure, but who cares. And for this exact reason I indicated that during cold season I drop tire pressure on both tires by a few psi - so they generate more heat during cold season.

Quite a stickler for the truth, but not for the spirit of the conversation.

And BTW it's tire "wear" and not "ware". See, I would've never mentioned because I understood what you meant, but I am mentioning it to support the spirit of your conversation... Very productive conversation.... Now, let's see what was the original issue... Ah, we are way past that. LOL Just shaking my head.

Switching to something positive...Did I mention in the past 15 min how much I love my turbo? Those short bursts to somewhere under 200 within a few seconds. No amount of cornering and knee dragging can replace that. Sorry Nic, LOL.. Your time will come.
 
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The Gribbler

Registered
Tuff, you are confused. But you are right - I didn't phrase it correctly. I didn't mean the front will literally have more traction. I meant I prefer to shift the bias in favor of the front having more traction that it would with higher pressure. Of all the people, you should know what I meant. So, once again - not bumping the rear pressure, but dropping the pressure on the front a bit.

And having high pressure on the front will eat the middle of the tire at the higher rate because the same weight is sitting on the contact patch of the smaller size. And yes, the tire will run cooler with higher pressure, but who cares. And for this exact reason I indicated that during cold season I drop tire pressure on both tires by a few psi - so they generate more heat during cold season.

Quite a stickler for the truth, but not for the spirit of the conversation.

And BTW it's tire "wear" and not "ware". See, I would've never mentioned because I understood what you meant, but I am mentioning it to support the spirit of your conversation... Very productive conversation.... Now, let's see what was the original issue... Ah, we are way past that. LOL Just shaking my head.

Switching to something positive...Did I mention in the past 15 min how much I love my turbo? Those short bursts to somewhere under 200 within a few seconds. No amount of cornering and knee dragging can replace that. Sorry Nic, LOL.. Your time will come.

Slowclap
 

snbusa

Registered
IG, yes, my want of turbo accelleration has long past the point of obsession. I'm looking forward to the day that we can take a 200 mph blast on the beach run.
 

IG.

Registered
IG, yes, my want of turbo accelleration has long past the point of obsession. I'm looking forward to the day that we can take a 200 mph blast on the beach run.

Not quite that fast... Somewhere, under 200...which could be 50, 55, or even...crazy fast at 60! Big brother is reading...Always. LOL

Lately, I can hardly avoid birds and cops. Both seem to pop out of nowhere. For birds, it's easy - just dunk in time...
 

snbusa

Registered
New question, I lost 35lbs since I had my sag and the rest of my suspension set up. I guess that it will work against my efforts to correct the cupping with lower air pressure. Please help. Thanks.
 

sixpack577

Top Gun
Registered
New question, I lost 35lbs since I had my sag and the rest of my suspension set up. I guess that it will work against my efforts to correct the cupping with lower air pressure. Please help. Thanks.

Losing 35lbs, I'de reset the sag.
 

IG.

Registered
I would just have a good meal and a drink before every ride. LOL

Seriously, I'd call the place which setup your suspension and ask for their recommendations. It will take them 15 sec to tell you how to adjust. I would imagine preload needs to be backed out a bit - maybe one turn on the front, and half a turn in the rear. Also, do you feel any difference when riding? If you don't, maybe leave it alone. Come winter, you will be packing extra weight in terms of extra clothing - so it will partially offset the difference in weight.
 

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