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Discussion Starter #1
Two things first:
1) To me this is a Technical subject so sorry if it needs to be moved.
2) The discussion is not intended to be a pi$$ing contest, but more a general sharing of tire wear knowledge as it applies to motorcycle tires.
Please keep it that way.

Waldo, thanks for the write-up at http://www.rattlebars.com/tirewear/
In the write-up you do state that it is not a Scientific study, but rather results from actual experience. Based on that, I'd like to get input from yourself and others on cupping (a.k.a. scalloping).

In the "Waldo" article it suggests that using higher air pressures will reduce cupping, but nothing will eliminate cupping. This may be why many folks will utilize pressures of 40psi (or more) in the front tire when 36 psi is the recommendation. The article further states that cupping is not a sign of bad suspension parts.

To add to this confusion, there are members running a G709 with stock suspension and those with upgraded suspension and neither have cupping (in my case-suspension upgrade, 36psi, no cupping).

It seems to me that since cupping appears the be caused by the tire "bouncing" on the road, that suspension would be a prime suspect, but maybe not

Everyone please chime in with their thoughts, and, try to give reasoning for your thoughts.

TIA to all for your replies.
 

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Current tires are being run with modified suspension. Front at 35psi has 9500 miles and is as smooth (but noisy in corners) as a new tire minus the molding nipples. The rear was replaced early (1500 miles ago) due to a nail, but at 37psi it too was smooth. These tires have a varied riding condition life and I'm very pleased with their performance, but have a different brand already mounted on spare wheels for the next go round.

Maximum inflation is not necessary for good performance and tire life, but proper spring rates/alignment are...just like good shocks/struts on a car/truck.
9500 miles @ 35psi (cold)
 

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I don't know if such could be found on the WWW or not, but my local Firestone store usta have a really neat store display chart showing various wear patterns for auto tires and the most suspect causes for each. Cupping and scalloping were differently defined with different causes. I had scalloping on my OE front Bridgestone way back when and the odd center rib wear pattern on a couple of E-3s; otherwise my fronts have worn very evenly - although there may have been some very minor scalloping if studied with great scruitiny. My rear tires scallop big time due to my riding style and I correct that on occasion. I have had no cupping since that OE 'stone on the front.

prs
 

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It is mine viewpoint and understanding that if your tire is noisy in the turns then they have uneven wear... usually it's due to cupping.

Honda is unaware of what tire is on your machine so their recommended inflation numbers are invalid. It is important to use the tire inflation numbers that are marked on the tire itself.

I will also say that the rear tire will show signs of cupping feathering scalloping any combination of those 3 due to the fact that it is the tire used for acelleration and decelleration so it will wear differently than the front tire.

Again that is my understanding of the tires known characteristics
 

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I replaced my original Dunlop with a Metzler ME880 Bias when I went dark at 15k miles. Traxxion springs, rear shock and All Balls were installed at about 2k miles. When I replaced the Dunlop I didn't notice any cupping and the tire was at or just past the wear bars. I'm ready to replace the Metzler with a Battlax BT-45 rear tire. The Metzler is showing some cupping and for the first time since owning the bike I get the dreaded wobble. I've always run 36psi in my front tire. It may be time to get the front suspension looked at by a pro because all seems good to me.

Note, I very rarely ride with hands off the bars without the cruise set, it just happened that I was adjusting one of my gloves.
 

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Richard,

I have cupping on my front tire, a Metz 880. No suspension upgrade (yet). It started about 2500 miles ago and the tire now has about 8500 miles on it. It hasn't gotten worse and I still have a lot of tread left. It should make it to 12K, I'm thinkin.

I read Waldo's article, too. Good article but I don't agree with some of it.

I just can't buy the hypothesis regarding left front/rear tire wear. I understand that's not what this thread is about. Do I have an alternate hypothesis about that kind of uneven wear? Not really. I just think the left turn vs. right turn hypothesis and each turn's effects on tire wear are negligible... especially at the speeds at which those particular turns might have an effect (tight turns, most commonly found at intersections, if I understand his theory. If I don't, someone correct me). All other turns would be equal. Could it be crowned roads? Doubtful, since the effect would be negligible, too. Slight misalignment? More likely.

Do I have an idea why the center of the tire might wear quicker than the outer edges? Lack of twisty riding or riding mostly on slabs or straight roads is my thought.

I also think cupping/scallopping is affected by suspension and braking, as well as ambient temperatures, inflation pressure and tire brand. I'm not sure you can narrow it down to one reason, or even two. I run my front at 41psi and always have. Cupping/scallopping is a subject that's been debated for years and it'll continue that way, I'm sure.

No offense to Waldo; I appreciate the time and effort it took to write and post it. :thumbup: I just disagree with some of it. I hope that's not considered pissing. Not trying to... just trying to be in the discussion.
 

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My wife and I have over 320K miles on the current level GW. 90% of those miles were on Stones. I run 40-40 psi, and have had NO cupping of any kind on any of these tires. Our best front ran over 28K miles, and our best rear ran over 20K. On the 01, Honda replaced the oem stem bearings at 88K, at 160K they said the next change was on me. I installed All Balls at that point. I do not like All Balls for pulling a trailer. On the 07, I replaced the oem stem bearings with an oem trike set that was removed for a rake procedure. We have 3K miles on the 2012, that came with Japanese Stones, made in 9th week of year 11.
 

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I don't think ALL tires will cup. I had cupping on my 08 with the OEM tires, I replaced the with E3's and the same thing, I them put All Balls in and switched to stones 709 and 702 and had zero cupping at about 9,000 miles.
I have about 4,000 miles on Bridgestones 023 on my Concours 1400 with zero cupping, stock front (021) was gone at 3500 miles, no cupping but was at the wear bars, rear tire (021) was replaced at 5500 miles, no cupping but was going on a trip so I replaced it because it was close to the wear bars. On the Concours site you never hear anyone complain about tire cupping.
 

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IronMan
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Just my 2 cents but more air pressure means less rubber on road so less chance of cupping 40 lbs on e 3 front 15,000 miles no issues teeth do rattle a little lol if i'm on slab n bad weather (all day ) i will take 2-3 lbs out - to me a little more on the road safer
 

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I just can't buy the hypothesis regarding left front/rear tire wear. I just think the left turn vs. right turn hypothesis and each turn's effects on tire wear are negligible... especially at the speeds at which those particular turns might have an effect (tight turns, most commonly found at intersections, if I understand his theory. If I don't, someone correct me). All other turns would be equal.
If I travel double the distance then I have double the wear. Left turns in this country are pretty much double the distance of right turns thus the left side of your tires will wear faster.

How can you not accept this?
I also think cupping/scallopping is affected by suspension and braking, as well as ambient temperatures, inflation pressure and tire brand.

No offense to Waldo; I just disagree with some of it. I hope that's not considered pissing. Not trying to... just trying to be in the discussion.
The ambient temp does not matter *MOST* of the time as within a few miles your tires are hotter. Those who ride in cold weather will have more miles to run before the tires are up to temp.

Most motorcycle riders are clueless on the temps their tires actually run. I think you would be surprised at just how hot our tires can (and do) get if you are not aware of just how significant the temp shift can be on the wing.

Of course heat increase = air pressure increase. General rule is 1 PSI per 10 degrees. That's why doing a typical pressure check with the tires hot is a false reading....

Air Temp = 70 and the tire has been sitting for a couple of hours then it's fair to say it's at the cold inflation point and should be checked here.

Air temp = 100 and the tire has been sitting for a couple of hours then it's fair to say it's at an ELEVATED cold inflation point and CAN be checked but you will need to subtract 3 PSI to account for the additional 30 degrees of air temp to give you an accurate reading.

Example:
70 degrees, cold tire, 45 PSI
100 degrees, cold tire, 48 PSI

BOTH pressures ARE CORRECT even though they are off by 3 PSI because the temp is off by 30 degrees.

Now let's really add some heat.... You checked your tire in the morning at 70 degrees and it reads 40 PSI just like you like it to. A few days go by and then you go for another ride and the tire's temp jumps to 140 degrees. You pull off at a gas station and check your pressure, after remembering that you had forgotten to check it that morning, to find it's reading 47 PSI. You think it's over pressure and let some out. Let's say you put it back to 40 PSI. Once the tire has cooled off and is back to its cold inflation point you are now 7 PSI under-inflated and have a tire with 33 PSI.

There's a bit more to this tire pressure thing that many people are aware of. Some riders think they pay really good attention to their tires but some riders do not and because they are not aware of the above they easily end up with under inflated tires which is one of the leading causes of cupping.


I hope that might shed some light. Dunno.

Again, the above is my understanding so if anyone thinks it's flawed please let me know.
 

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If I travel double the distance then I have double the wear. Left turns in this country are pretty much double the distance of right turns thus the left side of your tires will wear faster.

How can you not accept this?
I agree with all your inflation pressure facts. Good stuff. I never check my pressure when the tires are hot. :thumbup: Learned somethin, too. Thanks.

But as far as left turn vs. right turns, I understand the distance thing, but basically you're sayin that you're turning left twice as much as you're turning right, or spending twice the time turning left as turning right. Hmmmm... don't think so. If you say no to that (that you make rights and lefts equally), then wouldn't your right turns be tighter turns with more lean angle, producing more friction and, thus, more severe wear on the right side?

Also, if the left vs right turn theory is true, then why don't ALL tires wear out on the left side first? Seems to me they would (and they don't). Also, car tires would have the same problems, and they don't, to my knowledge. Jus sayin'.

Sorry, still not buyin.

BTW... how do you check tire temperatures?

Good, healthy discussion.
 

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I do not claim to understand the physics of tire wear, but I do know that when I first purchased my bike it had the Dunlop 250's on it and the front and rear both were cupped fairly quickly. When I switched at my first tire change (at 8000 miles) to Bridgestones front and rear, I continued to have a tire cupping issue with my pressures set at 36 front and 41 rear. When I switched over to the darkside, the cupping completely disappeared. I now run the Bridgestone front down to the wear bars and it is as smooth as a babies behind. I ride 50/50 twisties to slab at around 15000 miles per year. When I changed the front springs to Progressive and updated the steering head bearings it did not create any change to my tire wear patterns.
That being said, this winter and spring I had the bike into the dealership a few times chasing noise ghosts in the engine. I put a Stone which has about 4000 miles on it, back on the rear for this process. I rode about 2000 miles with the cupped stone on the rear and started to notice cupping in the front again.:shrug:
 

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But as far as left turn vs. right turns, I understand the distance thing, but basically you're sayin that you're turning left twice as much as you're turning right, or spending twice the time turning left as turning right. Hmmmm... don't think so. If you say no to that (that you make rights and lefts equally), then wouldn't your right turns would be tighter turns with more lean angle, producing more friction and, thus, more severe wear on the right side?
Okay... You really need to read the wear article that was posted earlier in this thread. http://www.rattlebars.com/tirewear

In the USA we drive on the right side of the road thus turns to the right are a shorter distance than turns to the left which require us to travel across one direction of traffic to get to the other.


If I am at an intersection facing north and I want to go west, I have to cross over the eastbound lane(s). This is where the left turns are so much longer than right turns.

Even if you do factor in lean angles variances between right and left, though your lean angle *CAN* be greater turning right, the duration of said turn is a fraction of its' counter-part thus negating that argument.

Does that make sense now?

Cars--- it does happen to cars which is one of the main reasons why the tires need rotation.

It does happen to ALL tires but we do not see it in all tires because not everybody spends enough time doing intersections. Yes, I spend quite a bit of time doing intersections but I also ride crazy miles on the super slab and the twisties so it equals out. If all I did was city driving then I would wear the left side of my tires LONG before the right.

PLEASE read the tire wear article.
 

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I do not claim to understand the physics of tire wear, but I do know that when I first purchased my bike it had the Dunlop 250's on it and the front and rear both were cupped fairly quickly. When I switched over to the darkside, the cupping completely disappeared. I now run the Bridgestone front down to the wear bars and it is as smooth as a babies behind.
My results exactly as well.

I did change out the front springs and added a fork brace also.
I changed my original front and rear tires at 6,000 miles and they were a mess.

Jeff..
 

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I don't know if such could be found on the WWW or not, but my local Firestone store usta have a really neat store display chart showing various wear patterns for auto tires and the most suspect causes for each. Cupping and scalloping were differently defined with different causes. I had scalloping on my OE front Bridgestone way back when and the odd center rib wear pattern on a couple of E-3s; otherwise my fronts have worn very evenly - although there may have been some very minor scalloping if studied with great scruitiny. My rear tires scallop big time due to my riding style and I correct that on occasion. I have had no cupping since that OE 'stone on the front.

prs
I chose quickly this prs comment to which to respond for no reason other than he mentions two pertinent points.

The OEM front Bridgestone of which you speak was a 704 as was mine. That 704 cupped. They went to the 709 just before I bought my second tire and the 709s, while they will show wear along the tread pattern like all other tires, it does not seem to be as noticeable unless one looks at a 709 when the light is "just right" for it to be seen.

It is folly to compare auto tire wear to motorcycle tire wear because on an auto, you have three other tires to "support" the fourth and perhaps faulty tire which will bounce, hop, & wiggle because of the "support" it receives from the other three. No such support is provided on a two wheeled motorcycle.

If one wants to posit as the OP has that cupping is due in some way to the tire bouncing/hopping, one would have to explain why cupping WITHOUT FAIL follows the tread pattern invariably. If your tire was performing some kind of "micro hop" in turns, would you not feel that vibration as you would the vibration and noise that a cupped tire manifests?

Folks who have changed their suspension have changed the RAKE of the bike which greatly influences tire wear when the wheel is turned. Your wheel is turned in EVERY turn in the direction your bike is actually heading and rake plays a major part in how much rubber is scrubbed of the tire due to the forces involved.



I have heard so called experts claim that road crown is the cause of side tread wear. So much for "experts." I challenge you to find a road that is crowned at 20° and if you do, by all means present the evidence here.

 

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<...>That's why doing a typical pressure check with the tires hot is a false reading....<...>
Again, the above is my understanding so if anyone thinks it's flawed please let me know.
If your tire gauge compensates for temperature variations, then your pressure reading at 60F and at 100F ambient will be the same.

It's not a false reading if you know what the temperature of the atmosphere in the tire happens to be.

Tire pressure monitors do not normally take into account the temperature, so they will measure a corresponding rise in pressure - as a result of the change in temperature...or a change in altitude, which can cause similar errors in pressure measurements.
 

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Discussion Starter #19
Thanks Waldo...your reply appreciated.

Just to remind all, this is a discussion of moto tires. Don't want to get into debated over CT vs. MT.

Waldo, read comment about "micro bouncing". Since all tires bounce (to some degree) as we drive down the road, even if we can't detect it, would the suspension not play a role? Sorry if i seem dense here.
 

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DJ please don’t take this personal because it not... It’s not directed at you, you just used these phrases... :thumbup: :thumbup:

“In the USA we drive on the right side of the road thus turns to the right are a shorter distance than turns to the left which require us to travel across one direction of traffic to get to the other”.

I’ve been told this for many years now and to a degree I will accept this theory as being true, but I have yet in my many travels around the block, have I seen that all left and right curves have been created equal????

That being said, come here and ride a few of our twistys and see for yourself, you will find some that curve to the right that are very sharp and some that are extremely slow and the same goes for the left curves...

This theory doesn’t hold true unless all curves are created equal, and anyone that has carved a few curves through the mountains knows that, that just isn’t true...


“If I am at an intersection facing north and I want to go west, I have to cross over the eastbound lane(s). This is where the left turns are so much longer than right turns”.

I will complete agree with this facts in the turning radiuses but when you take in the speed difference when you make the two different turns and you will, it really doesn’t make any difference on your tire wear... :shrug: :shrug:

IMHO!!!
 
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