Tire Shaving, Flat Spot and Raised Tread Edge - Calling All Tire Whisperers

[gmcjetpilot]

The short question is technique to shave and contour tire. The front and back of by feel a slight flat spot. At  6K miles tread depth is good.  The front is a little more flat than the rear tire.. The rear if you look or rub your had over it one edge of treads is a little proud (sticking up by feel). If you look close at right angle you can see it is "feathered". I think all this is normal as under hard load the trailing edge of tread groove is digging into road. 

 

Tires are about 5 yrs old (I know just replace them). Only have 6K miles or mid-life (people report 12K. I know only 6K in 6 years but bike was not ridden for 3 years due to life an inop in tank fuel pump going Kaput. 

 

Finished 2800 mile ride over 2 weeks, and "chicken strips" are fairly small. I road fairly aggressive 14 days in the twistiness with 130 lbs of cargo and me, 190lbs Trip included WV RA rally, whole blue ridge, Deals gap twice, and Cherohala Skyway. plus lots of other twistiness. 

.

I did add pressure over the solo 32/36 recommended for two up riding, max 36/42. I compromised at 34 and 39.  I have lowered back to 32 and 35.

 

WHAT TOOLS AND TECHNIQUES SHOULD I USE to contour my tread. I'm thinking of a rasp on a board. To take the ridges off each side of flat area. No need to address the raised trailing edge tread groove on rear.. 

 

 

[Bernie]

Increase your air pressure and your tires will be rounder on their own.

[Skywagon]

37/42 solo. Bernie is spot on. 

[Red]

however your contact patch will be smaller, eh? which has other ramifications. 

[dirtrider]

13 hours ago, gmcjetpilot said:

The short question is technique to shave and contour tire. The front and back of by feel a slight flat spot. At  6K miles tread depth is good.  The front is a little more flat than the rear tire.. The rear if you look or rub your had over it one edge of treads is a little proud (sticking up by feel). If you look close at right angle you can see it is "feathered". I think all this is normal as under hard load the trailing edge of tread groove is digging into road. 

 

Tires are about 5 yrs old (I know just replace them). Only have 6K miles or mid-life (people report 12K. I know only 6K in 6 years but bike was not ridden for 3 years due to life an inop in tank fuel pump going Kaput. 

 

Finished 2800 mile ride over 2 weeks, and "chicken strips" are fairly small. I road fairly aggressive 14 days in the twistiness with 130 lbs of cargo and me, 190lbs Trip included WV RA rally, whole blue ridge, Deals gap twice, and Cherohala Skyway. plus lots of other twistiness. 

.

I did add pressure over the solo 32/36 recommended for two up riding, max 36/42. I compromised at 34 and 39.  I have lowered back to 32 and 35.

 

WHAT TOOLS AND TECHNIQUES SHOULD I USE to contour my tread. I'm thinking of a rasp on a board. To take the ridges off each side of flat area. No need to address the raised trailing edge tread groove on rear.. 

 

 

Morning  gmcjetpilot

 

I almost never get 6,000 miles out of a tire so personally if I got to 6K I would just ride them as is then replace before next road trip.

 

Now to answer your question, whatever you use, or do, then you need to do to the tire with it spinning. If you try to do it spot by spot the tires will most likely end up with run-out, balance issues, & 1st order harmonic issues. 

 

I have re-contoured a few tires in my long life but I try to stay away from doing it when I can find another way. 

 

I typically use an air powered right angle grinder/sander  with a 5" 60 grit disk or a 7" 60 grit disk (7" disk works better). That will definitely reshape the rubber but will leave it a bit rough. I typically just leave it rough but if immediate looks bother you then go over it with an 80 grit or even a 120 grit.

 

An air powered right angle grinder/sander works better as those don't have air cooling slots or brushes for the rubber to get into & have a lot better (more precise) speed control, but most (at least mine) take a fairly high air supply CFM to keep up. 

 

The reason I usually just replace, or ride as-is, is because using any sort of grinder/sander makes a sticky gooey mess that sticks to EVERYTHING. If done on the motorcycle it makes a mess, totally ruins your clothing, gooes up your face shield & head covering  & makes a mess on & around the motorcycle. 

 

I usually wear one of my old outdated hazmat suits that were replaced due to age then donated to me. 

 

The wheel/tire should be removed from the motorcycle if possible as it does make a mess even with most of the motorcycle covered. I have a stand-alone spin stand that some wheels will bolt onto (built that long ago to mount my ice racing wheels-tires on to make installing ice studs easier). 

 

If no way to mount remotely then everything on the motorcycle needs to be covered as the rubber that the sander removes is pretty darn sticky from the sanding heat.  

 

If done on the motorcycle and the sander is used correctly it will keep the front tire spinning as it sands, or on the rear sometimes it will spin the wheel OK (works much better on chain drive motorcycles) but the rear can be spun using the engine on a shaft drive).

 

As I mentioned above it does make a mess so it has to be a special case to go to all the trouble.

 

If you try to do it without smoothly spinning  the wheels when shaping the rubber I doubt you will be happy with the results.  

 

A lot of that step wear comes from using dual or triple compound tires as the rubber durometer changes from softer to harder so it leaves a step in that area as it wears.  

[Lowndes]

I use a portable belt sander with an 80 or 120 grit belt to knock the shine off of brand new tires, a pre-ride "break-in" on the bike, wheels free to rotate while "sanding".  Not near the mess Dirtrider describes, just enough to make the surface ALL the way around look "used" (broken in).  Even the rubber tits are still there, mostly.  That way I can "hit the ground running", not worrying about breaking in slippery tires.  After that I strictly use asphalt and concrete to shape 'em.   Too flat on the bottom??    Time to hit Wolf Pen Gap and the RBR!!  Oh Boy!!

 

You know how they make the steel balls perfectly round for ball bearings??   Rolling them on gritty surfaces.

[Mellow]

26 minutes ago, Lowndes said:

Time to hit Wolf Pen Gap and the RBR!!  Oh Boy!!

Wooohoo!.. love those.. can't wait 'til April when I can get back there.

[dirtrider]

47 minutes ago, Lowndes said:

 

You know how they make the steel balls perfectly round for ball bearings??   Rolling them on gritty surfaces.

Morning Lowndes

 

That works for ball bearings as they are the same hardness all the way around. Imagine what they would look like if some spots on the ball OD were softer than others.  

 

Once a motorcycle tire gets step wear you really can't ride it out as you keep transitioning across that step so it keeps wearing on the softer side. 

 

The larger the step the more the tire scrubs as it drops off of the larger diameter step onto the smaller diameter next to it. The step & the rubber next to it are spinning the same RPM but the raised step is trying to cover more distance for each revolution than the smaller area that it transitions onto. 

 

Maybe a huge parking lot & rider that can hold a perfect line that only allows the raised step to contact the pavement. Lots & lots of circles later it might knock the step down a little. 

 

 

[Hosstage]

6 year old tires I wouldn't even bother. Ride them until you can't stand it any longer and replace them, or just replace them right away and be done with it.

Were you racing, and every 1/10th of a second counted, profiling tires might be worth the effort. If the tires were newer, and you planned on keeping them for another couple years and 5000 miles, it might be worth it. But for me, new tires would be the order of the day if they really bothered me.

[The Fabricator]

Why shave the tires?

By the time [mileage] that my front tire starts handling poorly, it's practically gone any way.

[gmcjetpilot]

5 minutes ago, The Fabricator said:

Why shave the tires?

By the time [mileage] that my front tire starts handling poorly, it's practically gone any way.

That is your take. The point woukd be delay that start of "handling poorly" and get another 1000 or 2000 miles out of it (in theory). But point taken. Just asking. I may buy tires, have them ready and experiment, see if I can hone a skill and get good results. It is just short of the feeling like it's falling off step. If I drove it straight all the time I coukd do nothing. However sporty lean angles the step can affect the handling, as yku know.

[gmcjetpilot]

I did not think more pressure the better for keeping tire round not with steps and flat. That seems counter intuitive. I think with high pressure it only will help if you turn (lean). If you do straight all day and shallow turns it will not help.  I can feel loss of patch area. That or I'm imagining it. There is a feel difference. 

 

THREAD DRIFT ALERT 

As I say above I'll start shopping tires and may play with tire shaping.

SUGGESTIONS?

Michelin has

Road 5 and Road 6 and Pilot Road 4

 

Not married to Michelin but had good luck. I want good wear with sporty riding but not track day rubber that lasts 1000 miles.

[Hosstage]

There are a few tire threads going that discuss all the tire brands and models, pros and cons.

[Skywagon]

GMCjetpilot..... I'm one of those guys who gets 12k-15k out of tires.  I've had Continental, Michelin 3-4-5, and currently Bridgestone T-31's.  I live in Houston where the roads are long, fast, and mostly straight.  I get out to the country to ride as soon as I can leave Houston freeways.  I never ever run below 36/42 and sometimes run 38/44.  The Michelins have had some cupping, So far the T-31's at 5000 miles look fine.  The T-31's are much quieter.  I hope they make 12K.  I'm not a beast on the bike but I do ride pretty spirited and do lean the bike a good bit...not Marc Marquez lean, but pretty good.  I do ride fast.  Our speedlimits are as much as 85mph.

 

Regardless of how much surface of the tire you have on the ground, one of the big factors in tire wear is heat.  Just watch MotoGP for a demo.  The 32 pressure you are running may...and I say may be part of the problem.  Heat build up will be greater with less pressure and if deflated enough, the center starts moving inward more than the edges as it is softer; and the edge of the tires are what is touching.  

 

There is no perfect answer.  If 32 works for you then 32 is what you should use.  Im another supporter of not running tires that are more that 4 years old as the carcass begins to harden and causes more heat.

[9Mary7]

8 hours ago, Skywagon said:

Heat build up will be greater with less pressure and if deflated enough, the center starts moving inward more than the edges as it is softer; and the edge of the tires are what is touching

This......^^^^^^ Low pressure with Michelin soft sidewalls is no bueno....(In my experience)

[Lowndes]

On 10/12/2023 at 8:22 AM, dirtrider said:

Morning Lowndes

 

That works for ball bearings as they are the same hardness all the way around. Imagine what they would look like if some spots on the ball OD were softer than others.  

 

Once a motorcycle tire gets step wear you really can't ride it out as you keep transitioning across that step so it keeps wearing on the softer side. 

 

The larger the step the more the tire scrubs as it drops off of the larger diameter step onto the smaller diameter next to it. The step & the rubber next to it are spinning the same RPM but the raised step is trying to cover more distance for each revolution than the smaller area that it transitions onto. 

 

Maybe a huge parking lot & rider that can hold a perfect line that only allows the raised step to contact the pavement. Lots & lots of circles later it might knock the step down a little. 

 

 

Dirtrider,

 

I think you're onto something here, maybe a big MARKETING OPPORTUNITY.  "PROGRESSIVE TREAD COMPOUND" - no more abrupt changes in tread rubber, harder in the middle for long wearing with progressively softer to the edges for traction where you need it most!!  AND no more steps in your tires from abrupt changes in compound.

 

Better get a patent and a copyright on the name.

[dirtrider]

17 minutes ago, Lowndes said:

Dirtrider,

 

I think you're onto something here, maybe a big MARKETING OPPORTUNITY.  "PROGRESSIVE TREAD COMPOUND" - no more abrupt changes in tread rubber, harder in the middle for long wearing with progressively softer to the edges for traction where you need it most!!  AND no more steps in your tires from abrupt changes in compound.

 

Better get a patent and a copyright on the name.

Morning Lowndes

 

That is already available in some motorcycle tires. It helps a little but you just get wider steps with a flat center. Mulyi-compound, progressive compound, tri-compound, dual compound are all used in some way or another now.   

 

Progressive compound tires are a help to some riders as it allows a harder center section with progressively softer side rubber for cornering. (great for long-haul freeway riders or mostly straight line riders).  But step wear can be still an issue to contend with as good part of riding for some riders is straight up.  

 

Personally, I waited as long as I could using single compound tires as I used to wear single compound tires pretty evenly.  

 

 

[Hosstage]

Heavy cruiser tires have been available in dual compound for at least a decade.

[lawnchairboy]

On 10/12/2023 at 7:12 AM, dirtrider said:

Morning  gmcjetpilot

 

I almost never get 6,000 miles out of a tire so personally if I got to 6K I would just ride them as is then replace before next road trip.

 

Now to answer your question, whatever you use, or do, then you need to do to the tire with it spinning. If you try to do it spot by spot the tires will most likely end up with run-out, balance issues, & 1st order harmonic issues. 

 

I have re-contoured a few tires in my long life but I try to stay away from doing it when I can find another way. 

 

I typically use an air powered right angle grinder/sander  with a 5" 60 grit disk or a 7" 60 grit disk (7" disk works better). That will definitely reshape the rubber but will leave it a bit rough. I typically just leave it rough but if immediate looks bother you then go over it with an 80 grit or even a 120 grit.

 

An air powered right angle grinder/sander works better as those don't have air cooling slots or brushes for the rubber to get into & have a lot better (more precise) speed control, but most (at least mine) take a fairly high air supply CFM to keep up. 

 

The reason I usually just replace, or ride as-is, is because using any sort of grinder/sander makes a sticky gooey mess that sticks to EVERYTHING. If done on the motorcycle it makes a mess, totally ruins your clothing, gooes up your face shield & head covering  & makes a mess on & around the motorcycle. 

 

I usually wear one of my old outdated hazmat suits that were replaced due to age then donated to me. 

 

The wheel/tire should be removed from the motorcycle if possible as it does make a mess even with most of the motorcycle covered. I have a stand-alone spin stand that some wheels will bolt onto (built that long ago to mount my ice racing wheels-tires on to make installing ice studs easier). 

 

If no way to mount remotely then everything on the motorcycle needs to be covered as the rubber that the sander removes is pretty darn sticky from the sanding heat.  

 

If done on the motorcycle and the sander is used correctly it will keep the front tire spinning as it sands, or on the rear sometimes it will spin the wheel OK (works much better on chain drive motorcycles) but the rear can be spun using the engine on a shaft drive).

 

As I mentioned above it does make a mess so it has to be a special case to go to all the trouble.

 

If you try to do it without smoothly spinning  the wheels when shaping the rubber I doubt you will be happy with the results.  

 

A lot of that step wear comes from using dual or triple compound tires as the rubber durometer changes from softer to harder so it leaves a step in that area as it wears.  

I'm pretty sure I have witnessed @roadscholar using an angle grinder on a front tire that wasn't quite squeezing in between the front forks too well before....

[gmcjetpilot]

The big reason to NOT to do sculpturing on your tire:

 

> Getting it material off evenly to not change the balance

> Messy

 

The above can be addressed by taking off bike, putting it on center stand,  have helper rotate tire, while you hold belt or disk sander or sanding block on tire at the correct location. Messy can be handled. 

 

Reasons to DO IT, better handling in that transition area from flat to side. I am getting to the point where I notice it slightly. However I may have been under inflated at 32/36 the bottom of what the manual recommends for light weight riding.  I am going to increase the pressure incrementally. and figure out how that effects handling, from above comments. Thank you.

 

PS person with angle grinder, please stay away from my bike. Ha ha. 

[Hosstage]

51 minutes ago, gmcjetpilot said:

PS person with angle grinder, please stay away from my bike. Ha ha. 

It's ok, he's a professional!

[lawnchairboy]

That he is.   
 

and I hear tell he used to sling Porsches around race tracks pretty good.

[gmcjetpilot]

Don't laugh it kind of works. SEE PICS. Per suggestions on tire pressure I was running 31.5/36 as manual suggest for dolo no baggage. Per suggested above i ran close to max (for dual full bags) 36/42. I filled to 34/39. Two things: 1) Hated the ride, harsh (this is pre shaving); 2) the pressure went up 2 psi front and 2.9 psi back, so near max 36/42 recommended by owner manual (full payload). I have aftermatket TPMS (leepee) valve stem to smart phone BT App. Seem to be accurate enough. 

 

Anyway shaving I went easy and a little at a time. It was not as messy as I thought. I may try a sanding BLOCK and contour by hand sanding.  The belt sander spun tire and I dragged brake or with gloves drag the tire to slip on sanding belt, adjusting hiw much pressure the sander was pressedagaind tire. Two people would be better. The belt sander depending on angle wanted to walk sude to side... so holding it in position and dragging brake it tire by hand was awkward. Hey it's experiment 😉 

 

Note the pic of front tire showing the sanding marks is Intermittent. This was a light test. If results are good I'll go at it some more. Baby steps.  I am going to lower pressure a few pounds. I did not love the feel at max pressure, more harsh overall and turns not as well planted? It just felt different.

[Hosstage]

I was thinking it would be easier getting the wheel to spin consistently at say 500 rpm (wild ass guess) and applying the sanding block to the tire, lathe style, or spinning on a powered wheel balancer.

[9Mary7]