Grinding tires back to round

[ElevenFifty]

I have nearly 8K miles on my first ever set of Michelin PR2's. TONS of tread left on front and rear despite the fact that 7K were fully loaded 2up highway and byway miles.

 

The front shows no signs of uneven wear but the rear was a little flattened out and the trailing side of all the big grooves were about 1/4" higher than the leading side. I don't think this is 'cupping' and I really don't know the physics of it, but the roundness was gone. There was some slight vibration when leaned and I could feel the transition point in turns as the bike progressively leaned into the corner.

 

To their credit, every set of Metzler 880's that I wore out in the last 100,000 miles were ROARING by 6000 miles. The PR's are much better.

 

So ... the bike is on the stand getting a good cleaning and tune up ... and my examination of the tires shows lots of life left. I picked up my 4" angle grinder with flexible backing and a 60 grit disk on it ... kind of rig you would use to remove old paint and rust from a trailer, for instance ... and start playing with the tire. The initial result was so good that I ended up starting the engine, kicking it into first with a touch of throttle lock (remember the bike is on a stand, firmly strapped down so this is not a "watch this" moment) and just lightly reshaped the tire.

 

 

 

 

[na1g]

So how does it ride, sound and handle?

[Danny caddyshack Noonan]

Yeppers!

Just did that on the 11RT with a random orbital and 40 grit for the same type of trip and result on PR3s. I added a nice large air mover fan behind me to minimize the inhalation of carbon black...plus it was hot in the garage.

[RAINEY]

If I got 8,000 miles out of them I would feel like I got my $'s worth and just buy a new rear tire. It does however take me about a year and a half to put on 8,000 miles

[ElevenFifty]

Results were outstanding!

[RPG]

Personally don't think I would take a sander to any tire but if it works, then bless ya.

 

Been running Dunlop Roadsmart's now for the past few years on my RT.

 

Most noticeable is their better wear pattern and total lack of howling when leaned off center, even at the end of their tread life.

 

just my $.02.

 

RPG

[eddd]

I'd just take it to the track. Same results and lots more fun.

[Polo]

Personally don't think I would take a sander to any tire but if it works, then bless ya.

 

Been running Dunlop Roadsmart's now for the past few years on my RT.

 

Most noticeable is their better wear pattern and total lack of howling when leaned off center, even at the end of their tread life.

 

just my $.02.

 

RPG

 

Here in Central Texas, going anywhere is the equivalent of taking the tires to the sander. Just sayin'...

 

[Kathy R]

This is a revelation to me. I never knew folks rounded out the corners after slab riding, but I have to admit I understand the desire.

 

Whenever I went on long trips I would put new (soft) rubber on the bike and slab it. When I got where I was going the riding usually took care of the edges, but I was one up.

 

I guess this never was a problem to me, because the brand of tires I used were SOFT and so the EDGES weren't an issue.

 

The Dunlops I used to use on my early bikes were the type that would be a problem. On those tires I'd come back from slabbing and the dang tire would give me the willys as I tipped over to make a tight turn.

 

But I never had that with the softer compounds?

 

My first reaction to reading this thread about sanding the tires was shock. I wondered if this compromised the tire in some fashion? Waiting to read replies here I see it's not an issue. Good to know. I learned something.

 

In my humble experience, sticky tires just need a scrub on some tight turns. Even if that means a parking lot of imaginary corners. I'm too scared to sand my tires. The whole thing just makes me think of a facial gone wrong.

[Danny caddyshack Noonan]

Grinding rubber to form is an old process. Tire "truing" shaving was very common, might still be, in showroom stock racing. Cutting with hot knife is done as well.

I've seen cured and uncured rubber ground down to shape on a vertical CNC lathes to meet a specific profile prior to being wound into a composite rocket motor case. We frequently abrade the interiors to allow for bond adhesion of propellant.

 

The process of sanding is pretty straightforward and does no damage to the rubber, with the exception of that which is removed. The heat is very, very low compared to a slab run where the tire is constantly flexing under load. The forces are virtually nil compared to riding in general and especially braking or hooning.

 

[Kathy R]

This just blows my mind, Peter. In a good way. I had no idea you could do this to tires and not compromise them. Thanks for the eye opener.