chuckb

What is a reasonable spec for radial runout or "out of round" for a good tire, properly installed on rims that are true?

I have Schwalbe Ultremo ZX on Zipp 101 wheels. The wheels are true and round, but if I spin the wheels, I can see a clear bump (~2mm in front, 1 mm in back) in the tire as it spins. (Doing the same eyeball test, with a mm scale ruler held by the wheel, the lateral and radial variation of the rim is under 1 mm, probably closer to 0.5)

I've had issues with vibration/shimmy on the bike (Cervelo R5). Truing the wheels helped, but on the last ride, I thought I could feel a sort of pulsing vibration on a descent. That's why I looked at the wheels/tires.

I've read about the issues with Schwalbes and I'm seriously thinking of going back to the old reliable, Continental 4000.

Can anyone shed light on what a reasonable expectation is for radial runout of a tire?

rhenning

Tire is not fully seated on the bead is the most probable cause. Roger

fietsbob

Depends on obsessive level. deflate and re seat high spots till satisfied ..

FBinNY 

I don't know if there's a standard per se, and how a tire varies is as last as important than how much. A tire that varies in a long trend may not affect riding, but one with a more local variation will be a serious issue.

As others said, I'd try reseating the tire and work it around sreading away from the high spot and get it as good as I could. If that wasn't good enough, I'd switch to another brand tire.

chuckb

I did deflate and reseat it several times, to no avail. The bump is pretty localized; if I spin the wheel and hold a marker just above the wheel outside surface, I get a mark that is about 15 cm long, which is 6% of the wheel perimeter, so it's pretty localized. The clincher is that the rear tire has the same symptom, although not as badly, and a hairline crack in the sidewall.

Took it to the LBS this morning they are putting new tires on it, the questions asked. I'm going back to Continentals and won't use Schwalbe again. The Ultremo ZX is a nice light tire, but not durable and Schwalbe still seems to have serious manufacturing issues. These tires had less than 300 miles on them.

DCB0

Ironically, I have found in the past that Conti tires are the worst in terms of being impossible to seat perfectly, especially wider touring tires. Their road tires kick butt, though.
Specialized tires - high rate of failed sidewalls and bead/sidewall interface, but the ones that don't fail are good.

Edit: When you did the test with the marker was the line always in the same spot on the tire or did it move around the tire when the tire was deflated and reseated?

FastJake

I've never had a problem with lumps in road tires, although I have never used Schwalbe. Usually they are so narrow that they only mount "one way." The tires I have more trouble getting to run true are fat MTB tires. In particular, one pair of 26x2.35 Kenda Nevegal's on some WTB Laserdisc rims are virtually impossible to get all the way seated. It's not a problem when riding, but it just looks so awful to see it be ~5mm off radially.

gyozadude

Each tire varies, but some brands have more runout than others, no matter how you mount them.

Percentage-wise, even the best made tires have about 5% - 10% variance between low-to-high points on a mounted casing. On a 20mm tire, this means +/- 1mm either in or out from the average. Seems like you're doing the right things with the marker and dismounting/remounting after turning.

My worst experience is with discount Vee Rubber tires. On road tires in 27 in. and 700c, they vary upto 20% and hit brake arches. I'm surprised by the experience with Schwalbes. I've found them very reasonable for runout in many widths, especially wider hybrid tires and have recommended them highly. They're better than Michelins for runout, which I was pretty impressed with already for having very well priced import road tires that had low runout. But each maker can have some bad ones and sometimes, it might be a whole batch that's just at the outer range of what will pass QC.

Hopslam

Had same issue with 2 conti 4 seasons they where replaced warrenty if you mark the bad spot ( on tire ) it's easier to know it's not a seating problem.

Cheers

FBinNY 

Tire seating used to be very predictable, it either was or wasn't with nothing in between. That was back in the days of Endrick pattern rims where rim had shoulders where the tire seated the same way auto and motorcycle tires do. This design provides very reliable seating because it's easy to mold tires for an accurate fit there.

Nowadays most road rim are hook edge, which offers the benefit of better hold at high pressure. The design grips the bead wire under the hook held there by the tire pressure. The problem is that many (most?) don't have well defined recesses for the hook, nor shoulders for the tire to seat on, and therefore have no mechanism to precisely locate the tire seat.

If you want better or more precise seating on hook-edge rims, I suggest you select tires where the bead forms a hook to the outside with a molded pocket for the rim's hook.

chuckb

Yes, I did that and the high spot was in the same place each time. LBS put Conti 4000s on today and they are round to less than 1 mm. Tomorrow I'll ride and see how it feels.

IthaDan 

Do you use nuts on your presta stems?