Topic: Front tire scalloped

[dave500]

actually ofreen is correct most tires are engineered to be able to be run 10% under or over inflated as for me D404 on my cb550 run at 68 psi and never any cupping I usually only get cupping if I run them lower for a softer ride and only on the front will they cup

68 psi??what is it a light truck tyre??

[Retro Rocket]

actually ofreen is correct most tires are engineered to be able to be run 10% under or over inflated as for me D404 on my cb550 run at 68 psi and never any cupping I usually only get cupping if I run them lower for a softer ride and only on the front will they cup

68 psi??what is it a light truck tyre??

WOW, try halving that and you will be close.......  Hit a pot hole with that much pressure in the tyre and its likely to explode....

[dave500]

thats how dannos 550 goes 125 mph,,or is that 125 psi if you add the front and rear wheel tyres pressures together?anyway it sounds like a lot of wind to me.

[Retro Rocket]

thats how dannos 550 goes 125 mph,,or is that 125 psi if you add the front and rear wheel tyres pressures together?anyway it sounds like a lot of wind to me.

You could be on to something there Dave.....   That is a ridiculous amount of air for a bike tyre

[TwoTired]

If you are running oversize tires on the stock rims, you will have to use tire pressures much higher than the original tires used.

As for the scalloping.  Were the tires oversize on the rim?
Was it a tubeless tire mounted on a tube rim?
Was the bead seated correctly on the rim?
Was the correct tube used for the tire?
Was the tire balanced?
Are the spokes tight?
What tire pressures were used during the scalloping development?

[Retro Rocket]

If you are running oversize tires on the stock rims, you will have to use tire pressures much higher than the original tires used.

I beg to differ bigger tyres do not necessarily mean more pressure, it doesn,t work like that at all, my motorcycle has tyres with more volume than my mountain bike and run 34-36psi, the mountain bike runs around 50 psi,my 4x4 has even bigger tyres and runs the same amount of pressure as my bike. The only time where more pressure is needed is when carrying a load or for long distance rides where a constant high speed is used, then all you need to add is around 4 psi, any more can end up in disaster as the tyre will also go up in pressure when  hot. running under inflated will result in about a 30% increase in tyre wear. The correct tyre pressures are an important and often overlooked part of a well maintained bike..

[donpark1086]

Scalloping might be due to "inherent braking", but I don't know if tire manufacturers still us this term

[TwoTired]

If you are running oversize tires on the stock rims, you will have to use tire pressures much higher than the original tires used.

I beg to differ bigger tyres do not necessarily mean more pressure, it doesn,t work like that at all, my motorcycle has tyres with more volume than my mountain bike and run 34-36psi, the mountain bike runs around 50 psi,my 4x4 has even bigger tyres and runs the same amount of pressure as my bike. The only time where more pressure is needed is when carrying a load or for long distance rides where a constant high speed is used, then all you need to add is around 4 psi, any more can end up in disaster as the tyre will also go up in pressure when  hot. running under inflated will result in about a 30% increase in tyre wear. The correct tyre pressures are an important and often overlooked part of a well maintained bike..

You just want to argue and cast dispersions.  ...And didn't even comprehend what I wrote.  How convenient for your argument that you ignored the part about stock rims, just so you can argue a point not germane.

The stock rim bead seats are narrow.  Oversize tires force the seated bead width to pinch narrow, and this changes the side wall angle from bead seat to tread support, making the tire squirm laterally when using pressures that were correct for the stock size tire, or the oversize tire on a correctly matched rim width.  To compensate for the lack of support, the tire pressure must be increased to make the sidewall more rigid.

This has been covered and explained in detail in prior threads quite thoroughly.  But, some still prefer myth and conjecture to actual engineering and design facts.

Rave and rant on RR, as you always do.  Anyone who wishes to believe you is free to do so.  I won't.   
I try to provide the best information I can.  But, I am not responsible for lack of comprehension, or attempts to sully valid responses posted here.

[Retro Rocket]

Nice reply Lloyd, typically arrogant and pathetic  as usual.    You seem to like starting #$%* every time i reply to something you have posted in, even if you are wrong. I have had almost every possible combination of wheel and tyre you could put on a bike and started out in bike shops fitting tyre's, would you like to explain to everyone why monster trucks that have massive wheels and tyre's run 8-10 pound of air. Once the tyre is beaded normal pressures apply. I know that you are a smart guy but your #$%*ed up attitude just makes you come across as a bitter old man, try getting over yourself fool, my post was relevant and far from a rant.......  If you feel i responded just to discredit you then you definitely have an overinflated opinion of yourself...  My friend reading over my shoulder can't even work out why your answer was so rude and pathetic..... you make me laugh....

[Don R]

TT, I'm in my in the house in my tightey whiteys so I don't have the numbers but here goes-

tire not oversize
not tubeless
Bead appears seated properly, The PO worked in the tire shop where they were installed. Means nothing but he should know something about it.
Correct tube? wont know until I remove it. Maybe not even then.
Balanced- yes. still in balance? not sure.
Spokes tight, they appear to be, none are wiggling when I check but I was reluctant to start turning them.

[Retro Rocket]

The stock rim bead seats are narrow.  Oversize tires force the seated bead width to pinch narrow, and this changes the side wall angle from bead seat to tread support, making the tire squirm laterally when using pressures that were correct for the stock size tire, or the oversize tire on a correctly matched rim width.  To compensate for the lack of support, the tire pressure must be increased to make the sidewall more rigid.

I gather you have actually experienced this for yourself.? It also depends on the sidewall profile. I ran a Michelin AM48 rear in 140-70-18 on a hot k6 on a stock rim and it performed perfectly, more pressure was required to bead the tyre but after that normal pressure was used, i rode the wheels of that bike and so did the guy i sold it too. I also had larger tyres on my GSXR1100 with exactly the same results, and actually my gsx750 also had wider tyres. My experience come from riding the #$%* out of most every bike i have owned and experimented with since i bought my first 750/4 in 1979, 30+ bikes later i have never had a failure. I have a 4.5 inch rear rim in my shop that has a 180 on it and it was raced, same pressures and checked regularly with very accurate gauges. My Mate Greg Avery ran a 130-70-16 on the front of his {my} GPX750 race bike and everyone told him the same thing, "it won't work, heavy steering, wrong profile etc etc etc", it was by far the best handling bike i ever owned and a few of my old racer mates were blown away at how well that bike worked. Greg was an "A" grade racer and Australian champion. Sometimes you actually need to experience something to get an accurate account of what is really happening, not just rely on anecdotal evidence and hearsay. 

A lot of modern compound bike tyres scallop, it generally means that the tyre is doing its job and sticking to the road well, under inflated tyres will scallop worse, scalloping is common on modern crutch rockets and race bikes.... It will always follow the tread pattern.. Some tyres scallop a lot easier than others and is probably related to the compounds.....

[Retro Rocket]

nope my tires have clearly printed on the side do not run this tire under inflated 68 psi D404 high speed and yes they are slightly oversized the rear will tollerate being run at 42 psi but the front has to be run at 68 or it will scallop and to be honest the only time I can feel the rim from a chuck hole or something is if they are under inflated

my Dads valkirie  had D404 on it that said 42 psi on the side wall but I don't think his were rated high speed

All d404 are recommended to run 41 psi at MAXIMUM load, less if unloaded.....

http://www.dunlopmotorcycle.com/tirecatalog_tire.asp?id=37

[Retro Rocket]

my tires are rated high speed because I had a cheepie on it once (rear) and they are not rated for anything over 80 mph when you go 100 mph they loose air and then when you come to a stop they are flat at least I hope you come to a controlled stop the first time it happened to me and I sat at the stop sign with a flat rear tire I just about needed to get a new set of pants because if that were to happen to the front tire it could spell death for the individual riding (me) I also found out that bike tires that are not rated for speed can explode if taken up that high this was something even I did not know and I used to be a tire jockey

They shouldn't loose air at all, actually they should go up in pressure as they heat up, i think its about 1 psi for every 10 degrees or something like that {mermory isn't what it used to be}. You may have had a leak on that wheel or tyre. I only ever use "H" on older bikes or "V" rated tyres .
I don't know who told you to run 68 psi but that is dangerous, at speed that tyre could just explode or come apart.... 41psi is the maximum pressure and that is fully loaded....

Rating    Speed (km/h)    Speed (mph)
Moped    50    30
J    100    62
K    110    69
L    120    75
M    130    81
P (or-)    150    95
Q    160    100
R    170    105
S    180    113
T    190    118
U    200    125
H    210    130
V    240    150
W    270    168
ZR    over 240    over 150

[dave500]

better post a picture of this tyre danno or it didnt happen.

[TwoTired]

Spokes tight, they appear to be, none are wiggling when I check but I was reluctant to start turning them.

If you tap them with a screwdriver handle, do they all ring about the same pitch?

Otherwise, I got nothin' else from my arm chair, sorry.
I guess I'd check front to rear alignment, shock action, and tire pressure issues.

Cheers,

[TwoTired]

The stock rim bead seats are narrow.  Oversize tires force the seated bead width to pinch narrow, and this changes the side wall angle from bead seat to tread support, making the tire squirm laterally when using pressures that were correct for the stock size tire, or the oversize tire on a correctly matched rim width.  To compensate for the lack of support, the tire pressure must be increased to make the sidewall more rigid.

I gather you have actually experienced this for yourself.?

Yes

[Kevin D]

100/90-19 Bridgestone BT45 run at 30psi for 8000 miles.

The rear tire is toast and will be replaced over the winter.

I am undecided on this one:

[Don R]

Yep Kevin, mine looks just like that. TT, I will check the spokes with the ring test. thanks.

[dave500]

ive had three bt45 on the front do that as did my nieghbours mid 90s gsx750 time and again.

[Retro Rocket]

100/90-19 Bridgestone BT45 run at 30psi for 8000 miles.

The rear tire is toast and will be replaced over the winter.

I read somewhere the other night that Bridgstone has changed their recommended tyre pressures for BT45's, 36psi front and 40 rear..

Kevin, your tyres have been run under inflated which will cause or make scalloping worse....

[dave500]

i ran 36 front and rear,i dont use those tyres anymore.

[TwoTired]

i ran 36 front and rear,i dont use those tyres anymore.

Smart man.

[Retro Rocket]

that just proved the point LLoyd was trying to make under inflated tire over sized on a narrow rim thanks

That wasn't his point at all, it was about the type of rim Honda uses and his comment was that to seat the bead properly that the tyre would need more pressure to work, what i said was that it needs more pressure to bead the tyre then it can be run on NORMAL pressures. There are NO motorcycle tyres that recommend 68 PSI, NONE. For all intents and purposes the H rating and recommended pressures are what is important, there are too many things that can effect the tyre temps, no tyre will run at a constant temp, lower pressure will make tyre's run hot, so will summer temps, so will hard riding, the temps are a guide only. You are running too much pressure in the dunlops, they don't need that much pressure and in summer or ridden hard those pressures will be higher again, running the risk of damage to the tyre. Most all tyre's , car or bike , increase temp by around 10 degrees when up to operating temps.   Even a  couple of pounds of pressure extra can make a difference to how a tyre works and alter the way the bike handles. There is NO "C" designation on the BT45 that i know of and definitely nothing on their site here in Australia there is only M/C which designates Motorcycle tyre....

Some reading for you.....

http://www.totalmotorcycle.com/photos/tire-tyre-guide/Tire-TyreTech.htm

There is tons of stuff on the net that will back everything i have said here......

I know it was my old one because I put it on my kz 400 where it can run a lot less pressure and ride a lot nicer

That doesn't make any sense.....same tyre, different bike, same pressures...... Simple....

[dave500]

post us a picture of the tyre on the kz400 danno,maybe it was misprinted?or maybe its the year of manufacture or something else?

[TwoTired]

that just proved the point LLoyd was trying to make under inflated tire over sized on a narrow rim thanks

That wasn't his point at all, it was about the type of rim Honda uses and his comment was that to seat the bead properly that the tyre would need more pressure to work, what i said was that it needs more pressure to bead the tyre then it can be run on NORMAL pressures.

No, you're wrong.  And stop misrepresenting my posts.  You seem more interested in what you think I said instead of what I actually said.  You don't want to listen to me, fine.  Here are links from someone else.  Maybe you are more willing to hear someone else.  He calls it pinch angle instead of sidewall angle.

http://forums.sohc4.net/index.php?topic=19346.msg274080#msg274080
http://forums.sohc4.net/index.php?topic=56494.msg609309#msg609309
http://forums.sohc4.net/index.php?topic=31345.msg324750#msg324750
http://forums.sohc4.net/index.php?topic=19346.msg274041#msg274041

What I am saying, is that to if you put oversize tires on the stock narrow rims, you have to use higher than normal pressures to artificially strengthen the sidewall which limits the squirm that arises due to lack of support from the increased sidewall angle.

Tower put it this way with regards to putting the correct size tire on the a rim:

Because those old tryres were generally taller on the sidewall compared to equivalent width metric tyres, the height/overhang ratio (rise/run) would be correspondingly greater, and hence the angle of the overhang, as calculated by the arctangent of this ratio, would be smaller.  The smaller the angle, the more firmly the sidewall supports the tread, the less squirm on straight roads. 

Of course cornering stability is related to both sidewall rigidity as well as sidewall height, among other factors.  So, for any given angle less height is better.  Conversely, for any given sidewall height less overhang angle is better.
At some point there is a trade-off between the older taller tyres and the newer wider tyres, other factors such as bead-height notwithstanding.

When I had oversize tires on my SOHC4s, I noticed the squirm from the increased sidewall angle.  To help alleviate this, I found higher tire pressures helped.  Others, did too, and began recommending higher pressures for the tires than the manufacturer specified, when fitting oversize tires onto narrow rims.  The higher pressures are a "patch" made to augment the wrong choice of a tire too wide for the rim.  The stability increases, but the tire tread center wears faster as an artifact of having too high pressure in the tire.  New oversize tires with overinflation feel ok, until the tread squares off and then the handling suffers well before it wears out.
This practice works well for tire salesmen as they get to sell you more expensive oversize tires more often due to rapid uneven wear.  For some, it's just the price for having the bike look "cool" with fat tires.