Odd Tire Wear..maybe?

Hi All

First time poster, long time lurker here. I've got a question that I'm hoping someone might be able to shed some light on. Maybe it's a typical bike thing that I just don't know about but, I'm seeing a weird pattern on the front tire of my 81' Kz750 LTD. Every other lug is worn substantially more than the ones beside it. The tire seems like its in ok shape and has lots of tread on in, but I think I'm probably going to replace it because it freaks me out a bit. Has anyone seen this before?

I've attached a photo to give you the idea.

Maybe I'm just crazy?

That's very similar to the "Cupping" seen on tires. It's almost like small spoon shaped sections of tire was shaved away. Inproper inflation and other suspension problems can cause this.

Do you ride two up(passenger)a lot? or just by yourself? How old's the tires? Any instability on the road? Swing arm bushings/bearings in good shape? Steering stem bearings good?

Haz wrote: Hi All
First time poster, long time lurker here. I've got a question that I'm hoping someone might be able to shed some light on. Maybe it's a typical bike thing that I just don't know about but, I'm seeing a weird pattern on the front tire of my 81' Kz750 LTD. Every other lug is worn substantially more than the ones beside it. The tire seems like its in ok shape and has lots of tread on in, but I think I'm probably going to replace it because it freaks me out a bit. Has anyone seen this before?
I've attached a photo to give you the idea.
Maybe I'm just crazy?

Hello, Haz, and WELCOME to KZr and participation on the forum!

Here's what Dunlop says:

How can I keep my tires from cupping?

You may not be able to entirely avoid cupping. Tire cupping or irregular wear is a somewhat common occurrence on all vehicles. On a four-wheel vehicle, you are advised to rotate your tires periodically to even out wear. Unfortunately, you do not have this luxury with a motorcycle because front and rear tires, unlike those on a four-wheel vehicle, are not interchangeable.

However, there are steps that can be taken to minimize cupping and uneven wear on a motorcycle:

Maintain your motorcycle and particularly your front forks and suspension.

Avoid hard braking whenever possible. Braking causes the tire to grab and wear in one direction. When braking is applied to the front tire, the load transfer over-flexes the tire and increases the tendency for cupping and uneven wear.

Maintain your tire pressures. Underinflation or overinflation in motorcycle tires are significant causes of cupping and uneven wear, particularly in association with hard braking and/or trailer use.

Some of today's tires feature tread patterns and constructions that are less prone to cupping than the ribbed tires of old. The Dunlop 491, D401 and D402 touring and sport touring tires are good examples.

Tire companies can, and are, helping to minimize cupping and uneven wear but you, the rider, must do your part. Follow the aforementioned guidelines. How Much Run-in Should I Give a New Tire? When new tires are fitted, they should not be subjected to maximum power or hard cornering until a reasonable run-in distance of approximately 100 miles has been achieved.

This is necessary for a number of reasons. Replacements for worn tires with different patterns and construction will not react the same. Also, a new tire is stiffer than an old tire. The new tire has a rounder tread profile, different contact patch and "lean-over edge" than the worn profile of an old tire. The new tire will also not react the same in combination with its remaining tire.

Carrying out the required run-in will allow you to become accustomed to the "feel" of the new tires and tire combinations, so you are better able to achieve optimum road grip for use in high speed, high acceleration and handling situations.

I've also suspected that a warped front brake rotor evidenced by pulsing during brake application might also contribute to the cupping.

Good Fortune!

Yea it's normal to a point. All you can do is keep your pressures in check to minimize it. Suspension, tire balance, all this has little or no effect on cupping. Back in old days they ran ribbed tires to see less of this. You'll notice stock KZs have rib design front tire that doesn't cup, but not a great tire. Now they have block pattern tires, and they will cup, and cup more or less depending on how you ride. If you never use the front brake, never ride hard in turns cupping will be almost non existant. It''s braking and turns that cause irregular wear. You can take a pencil erasure and slide it across a flat surface and watch what it does, the leading edge digs in, the trailing edge more or less does nothing, so the leading edge will always wear faster then the trailing. You'll see the same thing happen on block tires.

Ah, yes. And now that I think of it, I did the fork seals and oil earlier this year because one of them started leaking. When I pulled the forks apart the old oil looked like it had been in there for a good long while, and the improvement was pretty noticeable afterwards. This tire was new at the beginning of last year but it would have done about 7kkm with the forks in that shape.

I don't ride with passengers a whole lot, and I haven't noticed any instability after the fork job. Steering head bearing was done at the beginning of last year and it still seems solid. But I do tend to favour the front brake, and hard in turns?? that's my favourite part!

It sounds like this isn't a huge surprise then, it just seemed strange when I finally noticed it because the pattern was so regular, it looked like it was meant to be that way. It had me wondering "Was the tire like that when I bought it?"

Thanks for the input folks!