New rear tire out of round?

[asellus]

tl;dr - did maintenance, things check out, rear tire wobbles, wheel looks fine

So I did a bunch of work on the bike this last week, including:
- new tires, sport demons
- swingarm lube
- chain cleaning (2-3k miles of neglect)
- alignment and chain tensioning
- shimmed cush drive, set to near-zero play
- clutch adjuster replacement

Everything's re-torqued to spec, the alignment is dead nuts on (what a pain!), the chain tension is on the tight side (~38mm), and the bike runs and drives wonderfully now. No more slack in the driveline, and I feel better leaning than I did on the bald K630s. Except, now, for the wobble.

Regardless of gear or rpm, the bike now shakes above 35-40mph. Not enough to be scary, but enough to give the "this road is extremely uneven" feeling. Turns out the rear tire appears to be out of round just a smidge. Running the bike in second gear on the center stand produces a slight wobble on the outer dimensions of the tire, while the rim of the wheel remains rock solid. I don't have a run-out gauge to test just how bad it is, but I'd estimate it's in the 1.5-2mm range.

Is this something that'll self-correct, or should I look into getting another new rear tire, or...?

[Triple Jim]

Were the new tires balanced? It's entirely possible you got an out of round tire. I put a pair of Sport Demons on my Moto Guzzi a year or two ago, and the front was out of round enough to feel in turns. It was minor, and I left it alone and wore it out. If it bothers you, I guess the dealer that sold it to you should be willing to let you return it and send you a new one.

It's unacceptable to me that a manufacturer lets out of round tires got sold, and I plan to avoid Pirelli tires in the future.

[asellus]

Yep, they were balanced. The rear balanced easier than the front in fact.

I'll ride on it a little more when it warms up to see how it fares.

[Alchemist]

FWIW, I've owned a few sets of Pirelli tires for my car. About 10 years ago I got one in a set of snow tires that was out of round - enough that the shop noticed it when they put it on, but not enough to be noticeable in the car... no noise, handling issues, etc. I'm not sure if it was Pirelli themselves or an intermediate supplier/distributor, but it was replaced with (just about*) no questions asked.

*there was a caveat about pro-rating based on wear, but as it was purchased new, it was replaced like-for-like due to minimal wear.

Probably worth a shot at contacting them if it's noticeable and bothers you.

[NinJim]

I'm suspicious of the tire seating on the rim.

Most tires have a small raised line around the tire, near where the bead and tire come together. It should have the same spacing from the rim, all the way around the rim. This usually happens with tube-in-tire, but can happen with tubeless.

Low tire beading air pressure is usually the cause. I usually go as high as 80psi. If that doesn't set the bead correctly, it comes back apart for another try.

If the seating is not correct, or incorrect just on one side, it can cause a "wobble" with a tire/wheel that balanced correctly.

Hope that's what it is.
Cheers...

[Zaph42]

Originally Posted by NinJim

I'm suspicious of the tire seating on the rim.

Most tires have a small raised line around the tire, near where the bead and tire come together. It should have the same spacing from the rim, all the way around the rim. This usually happens with tube-in-tire, but can happen with tubeless.

Low tire beading air pressure is usually the cause. I usually go as high as 80psi. If that doesn't set the bead correctly, it comes back apart for another try.

If the seating is not correct, or incorrect just on one side, it can cause a "wobble" with a tire/wheel that balanced correctly.

Hope that's what it is.
Cheers...

That's the best advice. I've had that happen before, and resolved it by popping the bead off, adding bead lube and popping it back on.

[asellus]

Yeah, the bead issue occurred to me last night. I'll check it when I'm in the garage later. He had to reseat the front once because the bead didn't want to pop, but the rear had no issues at all during the process.

I also rode on it a little bit last night and I think I might just be overly sensitive. I did go from near-bald K630s to brand new sport demons, after all.

Here's to hoping!

[ducatiman]

lubing and careful visual checking every inch of bead for seating is imperative AT TIME OF MOUNTING. Above and beyond hearing the bead popping.

[asellus]

Drove out about 25 miles to a freshly paved, known-smooth road and by that time the wobbling had evened itself out.

If it was the bead fully seating itself through a heat cycle, or just a little bit of wear that it needed, I don't know. But it's fine now. Sorry, I jumped the gun a smidge on this methinks.

Thanks all!

[NinJim]

You didn't jump the gun.
Dirt bikes see this all the time. With MX bikes in the 12-15 psi and Trials bikes in the 4-6 psi range, the beads are always slipping and losing their alignment.

Somebody else will have this problem, again. And think it's the end of the world. Nope, just the personality of the beast.

Cheers,