Topic: Front tire scalloped

[Don R]

I noticed my 76F has some wierd wear pattern on the front tire only. It resembles a car tire with a bad chord with the tread lifted in some areas and not in others. When I roll it on a dusty floor I can see a pattern in the dust. I'm replacing them anyway but wondered it this could be caused by anything on the bike? It got new fork seals, fluid and taper bearings last winter..

[Danno]

the shocks are bouncing too much if you used fork oil it is too light try the recomended oil which I believe is sae 20 to sae 30  I had the same problem till I used the heavier oil also you can add a couple of washers under the long spring to make it tighter use washers the same diameter as the tube (or real close) there are instructions here for the process and also instructions here on the forum for turning them into air shocks which is infinately more tunable

[HondanutRider]

This is a common trait on large, heavy bikes like the GL1800 - Goldwing.  The front (and rear also) tire on this bike will cup with mileage on all brands of tire.  Owners will try firming the front forks and the steering races, and all sorts of other remedies, but the problem will still appear as the tires wear.

The best explanation I have seen, attributes this cupping to the heavy weight of the Goldwing and its demanding performance that causes the tire tread to "squirm" around the tread blocks as it normally rolls down the road while upright.  I've found the cupping pattern to always develop along the outer sides of the tread, radiating from the centre portion.  I can tell when it starts to develop (as it now is just starting on my tires) whenever turning and leaning the bike over a howling sound begins.  Another symptom that is noticed is when letting go of the bars at slower speeds, a severe wobble will develop as the front begins to oscillate.  (Not normally done - just checking. )

Your bike is not a heavy Goldwing, so this cupping is not usual.  However, it may have been caused by running with too low a pressure, or with some other imbalances present.  I wonder if the old-style of parallel tread pattern for the front has some merit over a modern block pattern?

[RustyJC]

This is a common trait on large, heavy bikes like the GL1800 - Goldwing.

BMW K1200GTs such as my bike (see signature) came with either Bridgestone Battleax or Metzler tires.  The Bridgestones are notorious for "cupping" the front tire at around 2500 miles.  It seems to be a function of the block pattern tread design where the blocks deform enough during normal riding to wear a cup into each block.  You can see it, hear it and (worse yet) feel it as you ride the bike.  It will eventually get so bad that you can feel the handlebars bounce as you roll the bike across the garage floor.

I'm now running a set of Dunlop RoadSmarts on the BMW and don't see any evidence of cupping with about 4,000 miles on them.

Rusty

[Steve_K]

I had a 92 VFR and I would brake hard and often when I rode it and wore the front tire out at 5K miles.  The tire was cupped badly and it handled much better with new rubber.   Others who did not work the brakes as hard got more mileage.  I watched air pressures closely and maintained her very well.  I regret not owning her now. 
Steve

[Don R]

Thanks for the replies. I also wondered about the tune of the wire wheel. It looks fine. I've only owned it for a while but have put about 3.5k miles out of the 10,400 that are on it. I wondered about tread pattern also. This is a fairly smooth grooved modern looking tire but not a brand name either.

[dave500]

too low tyre pressure.

[Danno]

Do not tune or true your wheel till just before you put a new tire on the rim otherwise you will hate the result till you change the tire as far as the scalloping is concerned and heavy bike riders take note also

scalloping is a shock dampening problem it can be caused by too low of tire pressure such as in the heavy goldwing recomended tire pressure on the swing arm is 32-34 but if you put D404 dunlops on it and do not run recomended tire pressure on the side of the tire you will get this

it can also be caused by too low a dampening rate in the forks valve modification may be necessary

and lastly it can be caused by the spring becoming work hardened and or sagging

heavy bike riders have often times put so many accessories on their bikes that they are not even close to the weight they were engineered at and therefore require modifications to these things

however on a stock cb750 or any of the single overhead cam bikes it is rarely anything more than too light a shock oil or the spring in the tube has sagged

In case you are wondering I started out my certification as a mechanic in brakes shocks tires and suspension

[RustyJC]

The BMW cups Bridgestone Battleax fronts at 2500 miles, but not the OEM Metzlers, nor does it cup (according to my experience as well as other riders who have tried them) the Dunlop RoadSmarts or Michelin Pilot Roads.  The premature cupping seems to be limited to the Bridgestones - probably due to tread design, tread compound, casing stiffness or ?

My BMW has ESA (electronic suspension adjustment) which provides 3 spring preloads (solo, rider with luggage, 2 up) and 3 damping settings (comfort, normal, sport).  One of the ESA actuators can be seen in the photo below - it's the canister-shaped device above the left rider's footpeg and below the rider's seat attached to the top of the rear monoshock unit.  The front suspension is a Hossack dual leading arm design with an ESA-adjusted monoshock unit as well.  I normally ride using the rider with luggage preload (185 lbs) and "normal" damping setting (no pun intended) since the "sport" setting on the street feels like someone has welded the suspension solid over rough pavement, although it's fine for the smooth twisties!!  The reports of cupping on the Bridgestones do not appear to respond to any of these variables - in the case of these tires on the BMW K-GT, it seems to be just a misfit between the bike and that particular tire. 

Rusty

[KingCustomCycles.com]

Posted to wrong forum?  What is this BMW stuff? Had one, hated it, bought parts, hated it more, sold it.

[RustyJC]

Sorry, but the subject was front tire cupping.  It isn't just limited to Hondas.  I was sharing my experience with the phenomenon on a BMW in hopes that some of the lessons learned could translate over to the OP's question at hand.  If this offended you (which it obviously did), I sincerely apologize.  I'll keep my bloody mouth shut from now on - consider it a newbie mistake.

Rusty

[Retro Rocket]

Sorry, but the subject was front tire cupping.  It isn't just limited to Hondas.  I was sharing my experience with the phenomenon on a BMW in hopes that some of the lessons learned could translate over to the OP's question at hand.  If this offended you (which it obviously did), I sincerely apologize.  I'll keep my bloody mouth shut from now on - consider it a newbie mistake.

Rusty

No need to apologize mate, your post was in context and had absolutely nothing wrong with it at all.....

[Danno]

it is true that certain bikes hate certain tread designs and I personally think bridgestones are not good for any of my bikes however I have never had any problems with the d404 lines but the front will still cup at about 10,000 miles but this is because it should have been replaced with the rear at 8,000 miles and in my case it is also due to 37 year old sagging front springs

again though I can usually get about 14 to 16 k out of my front D404 tires the scalloping never gets too bad

I prefer to use the D404 on my heavy bikes too like my GL1000 and vstar

very nice BMW hope you find a tire that works well with it

[Don R]

I haven't added any weight to it so it's most likely low air press and/or tire design from what I've read here. I appreciate all the answers and opinions.
 I'll change to a heavier fork oil new tires and watch the pressure. Thanks.

[RustyJC]

very nice BMW hope you find a tire that works well with it

Thanks.  The Dunlop RoadSmarts are doing just fine.

Rusty

[MCRider]

Thanks for the replies. I also wondered about the tune of the wire wheel. It looks fine. I've only owned it for a while but have put about 3.5k miles out of the 10,400 that are on it. I wondered about tread pattern also. This is a fairly smooth grooved modern looking tire but not a brand name either.

You didn't mention how old the tire is. If its modern it should have a DOT code on it (Google DOT Code to learn howto read it.)  If its over 6 years, no need worrying about anything till you replace it. If the tire is old and hard it may cup regardless of what you do. And once they're cupped you can't fix it, so buy a  new one.

I would not suspect the wheel truing unless you can actually see the wheel is out of round. Most likely pressure, mismatch, low quality tire to begin with, or fate, as many have said.

[Rgconner]

Posted to wrong forum?  What is this BMW stuff? Had one, hated it, bought parts, hated it more, sold it.

*kicks KCC in the shin*

Use the damn /sarcasm tag, will ya?

You are scaring the natives.

[Don R]

Right on the age of the tire, it's going on 5 years. I don't really care about this tire, I just wanted to cure any condition that may ruin the new ones and maybe learn something along the way. I am interested in upgrades and may try a set of emulators too.

[70CB750]

I think you just didn't rotate your tires in prescribed intervals 

[Rgconner]

Right on the age of the tire, it's going on 5 years. I don't really care about this tire, I just wanted to cure any condition that may ruin the new ones and maybe learn something along the way. I am interested in upgrades and may try a set of emulators too.

Verify the steering bearings and wheel bearings too. That can cause odd wear patterns.

[MCRider]

5 years isn't as bad as it thought you might say. It may have just been a cheap tire not up to the strain. But its on its last legs now.

My experience and reading, its usually a combo of cheap tire, weight, braking, and under inflation that cause it. Poor suspension condition isn't quite as relavent as it might be on a car with 2 side by side.

But I've had some "premium" tires that have done it as well. K81, Dunlop, Bridgestones, I think sometimes its just bad luck.

A fork rebuild with emulators is something to be encouraged. Tire or no, you will appreciate the difference.

[Kevin D]

So... whats the right pressure for a modern tire on an old bike?

My CB750 manual calls for about 30psi, the Bridgestone website says 43psi.
My 8000 mile BT45 has been run at 30psi and is starting to show its age.
(picture later)

Unrelated MC pic from yesterdays vintage meet:

[ofreen]

I'll keep my bloody mouth shut from now on - consider it a newbie mistake.

Rusty

It will be too bad if you do.  I doubt anybody else had a problem with your post.  Don't let one guy put you off.

[ofreen]

So... whats the right pressure for a modern tire on an old bike?

My CB750 manual calls for about 30psi, the Bridgestone website says 43psi.
My 8000 mile BT45 has been run at 30psi and is starting to show its age.
(picture later)

A good rule of thumb is to start about 10% below the maximum value molded on the sidewall of the tire.  The pressure value on the sidewall represents maximum pressure for maximum tire loading, a condition you will seldom be riding at.  So reduce that number 10% and go from there.  Ride the bike and see how it feels.  Steering should feel neutral, with no squirming during turning and/or braking.  Too much pressure will feel harsh and negatively affect traction.  Experiment a little above and below that -10% value to see what feels and works best.

The values given in the owners manual or on a sticker on the bike are irrelevant as those numbers are for tires that don't exist anymore. 

[Don R]

Ah, yes wheel bearings. I going to do my 70 while it's down for welding and paint.  I may as well do both bikes while I'm at it.