How Do You Assess Rear Tire Wear Rate?

8k miles (and 2 months) ago I replaced my tires front and rear - with Pirelli Diablo - and they are truly wonderful. While checking my SWing for a 500 mile ride tomorrow I noticed the rear tire worn to the cord (see photo). I rode 450 miles last Saturday and 300 miles yesterday. I know I checked the tires before my Saturday ride (pressure and condition) - and definitely checked air pressure before yesterdays ride - but not so sure I carefully looked at condition. MC buddies told me that I would see a wear strip indicator before my tires were worn excessively - but I never did see a wear strip. I have been regularly checking pressure on these tires and it has not varied when checked over the life of the tire (run 36psi rear and 30psi front). I am surprised at how fast I got from 'I think they look OK' to 'These are a safety hazard'. The last couple of weeks I have been going 1500 miles a week - which in 2 weeks represents about 38% of my maximum tire life. Is the wear bar the darker color band that is about 3/4 to 1 inch wide? Did the wear bars wear out during one of my rides? How many miles do the wear bars continue to show? I would like to change the tires at least 1000 miles (maybe more if I should) before I get to the cord - so, how do I estimate this? My last set of tires were Avon Viper Stryke - and the Diablos are sooooo much better at gripping. I changed to Dr Pulley 24 gram sliders about 6 weeks ago and most starts now are a near full throttle twist accompanied by 'Wheeeeeeeeeeeee!' as off I go - maybe I need a little less 'wheee!' to get longer tire life. Any suggestions would be appreciated.

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Try leaning a bit more. That is certainly some wear on that tyre. What pressure were you using in the tyre? IMO it maybe a bit too high.

Cheers,

The 'Wheeeeeeeeeeeee' part might make a bit of a difference. While you're feeling the 'Wheeeeeeeeeeeee' up above, the tire is saying 'argh' as it twists and squirms on the asphalt to get you and your bike moving. It might make a difference.

When I put my first Diablo on my Burgman, the dealer had put 40 psi in it. I questioned them on it, and their reply was that they do that to all rear tires so you can get additional life out of the tires. They were getting a lot of complaints on tire life before that. So I think you're fine with the 36 psi, which is the max for the tire.

I've consistently gotten about 15K on my Diablo tires, but then I also live in a different area. The amount of wear will depend on road surface as much as anything.

How many miles did you get out of the Avon Viper Stryke? What psi did you use there?

Chris

Surely Dimond you must have noticed some lack of grip! I can tell when my rear is starting to drop off as the back end twitches slightly when I manoeuvre. There are also visual wear marks that give an indication.

Do you check your tyres before riding, I check both before and after a ride, even on a standard 50 mile commute to the work place.

That, (the pic above), is possible some of the worst wear I have seen on a tyre for many a year.

Still, as they say - it's your life.

I'd be embarrassed and ashamed to let my tyres deteriorate like that and not notice until they were worn down to the carcass. You get an ideal opportunity to visually check the state of tyres every time you check the air pressures.

When your tire is at 1/8" thick ,there is the ware bars that cross the thread strips.You are 3000 miles past that and a blow out can happen anytime. Do not ride before replacing your tire .

Get a tread depth gauge. Learn to do own tire work, get some experience. Never trust other people like dealers. Us Honda recommended pressures---bike shop people usually drive pickups.

6-8000 miles on scooter rear, be ready for change. develop feel for bike--most can feel the change in rear action as tire goes bald. Bald tend to not work so well in rain.

I look at my tires and did not see wear bars on them . Thread depth is good . I need a depth gage.

Question for the US riders.

What is the 'legal tread depth required'?

In the UK it is 1mm.

"The limit for a Motorcycle tyre is 1.0mm across three quarters of the tread and a ‘visible’ tread pattern of the remaining quarter."

The wear on that tyre shows how you ride, it also shows you overinflate.

lower air pressure yields longer tread life at the expense of high speed handling.

I have found 20 psi works well for me, i weigh 175 pounds.

higher air pressure enhances high speed handling at the expense of tread life.

Harry
from Atlanta

Old Sloppy wrote:

higher air pressure enhances high speed handling at the expense of tread life.

I found that with higher air pressure, the tires ran cooler. In the Texas heat, cooler tires really helped extend thread life.

honda_silver wrote:

...I found that with higher air pressure, the tires ran cooler. In the Texas heat, cooler tires really helped extend thread life.

Tires will wear in the center, just based on whether your riding miles are highway, or byroads. The higher pressure will allow the tire to run cooler, just as honda_silver wrote. You can tell the difference after a ride, just by putting your hands on the sidewall. Run the tire at 20 psi, and be prepared to burn your hands in summer temps. Run it at the max of 36 psi, and you'll find the tire is still cool.

I rode the SS1000 from Seattle to Drummond, MT last Friday. I was surprised to find that with 20 hours of riding time, my rear tire was still running only warm, not hot.

Heat will wear a tire quickly. The rubber gets soft and scrubs off quickly. If you put only 20 psi into a rear tire, it will increase dramatically, just like any underinflated tire will. The difference between starting at 36 and starting at 20 is the amount of heat generated.

Chris

Years ago I had a tubed tyre blow out on a motorway in Wales caused by a slow puncture and the heat generated by the under inflated tyre. Luckily I was in the inside lane and rode onto the hard shoulder as we call it, and braked sufficiently to bring the speed down. However it developed a serious wobble once the front wheel was running on the flat tyre and rim, and down I went.

My MZ had a broken screen, damaged fairing, the alloy front wheel rim was scuffed, and I suffered a badly grazed arm. Luckily for me other bikers returning home from the Dragon Rally saw me go down and stopped to help me, one even changed the tube in my front wheel and re-inflated it, and I was on my way again within the hour.

Maybe it's just my imagination but mc tires seem to wear non-linearly. They look good, good, good, holy *#$% how did it get like that.

This is a reasonable article on what the wear bars look like. I'm thinking you didn't know what to look for:

http://www.thebikersgarage.com/motorcycle-safety-tire-wear-bars/

I replace rear tires once they start to square off (you'll see the tire in profile becoming less rounded) - the handling seems better to me, but I'm sure others think I'm replacing tires way too soon because there is often plenty of tread left. I ride plenty of twisties (in fact that's *WHY* I replace them earlier - if it was just a superslab bike, handling would be less of an issue, but I like the bike to respond smoothly in the corners) and know how to lean fine, but still wear out the center of tires first (that's why the dual compound tires use a harder rubber in the middle), as I commute to work down highways which have more straight stretches than curves. I think that's pretty typical - the middle of rear tires simply wears faster for almost everyone using standard motorcycle tires.

As for lowering the pressure, don't do that. You'll generate heat as mentioned above and cause the internal tire structure to deteriorate (I wouldn't worry about the tread also deteriorating quicker - you can see that, but you can't see the inner structure of the tire coming apart until it is past the danger point). It can lead to a blowout (higher pressure generally doesn't cause blowouts - it's low pressure that does it because of heat). The low pressure causes more heat because the sidewall can flex more (and thus cause different interior parts of the tire to rub together, generating heat from friction), which a given point on the tire will do every time that point rotates such that the weight is being supported by it - I.E. once ever rotation (it's also why high speed riding reduces tire life because higher speeds cause more heat inside the tire). Even if lower pressure prolonged tread life, I don't want to put my life at risk with a blowout. That's also why I check tire pressure before every ride - life is precious.

realbtl wrote:

Maybe it's just my imagination but mc tires seem to wear non-linearly. They look good, good, good, holy *#$% how did it get like that.

Very well put!

I've gone from thinking the tire is okay to looking almost as bad as the one pictured in the OP's posting on a 300 mile ride.

FWIW, I have had original IRC, two sets of Diablos and one set of Metzeler. By the looks of it, I will get the worst lifespan from the Metzelers. I got 7300 on the IRC (some put on by original owner), about 6500 on each Diablo rear, and have 4000 on the Metzelers currently and do not think I can get another 2500 out of them.

People on the MP3 section of Modern Vespa forum are swearing by the new Michelin Power Pure, a dual density tire.