Wobbly tyres (Avon Storms)

**Bnonn** · 18th April 2007, 16:26

K, so I got a new set of Avon Storm STs put on today (120/70-Z17 front 180/55-Z17 rear). I was expecting great things, but I also knew from reading a review here that some people have experienced a sort of wobble or wiggly feeling on them at low speed.

Well, count me among them. It feels as if the tires are heavier on one side than the other. It causes the bike to feel as if it is wiggling as you're riding along, and the effect becomes more noticeable the slower you go. The bike also seems to drift to the left if I take my hands off the bars. I tried it on a couple of different roads to be sure this wasn't caused by the camber, and while I can't be certain, I don't think it was. The wobble and drift ain't major—I don't think it is likely to affect handling. But it's disconcerting; and the fact that I don't know it won't affect handling is worrisome.

Does anyone know what causes this? Evidently it's a common issue with these tires. I got the Storms because they've received very good reviews in terms of wet handling, as well as longevity; and they were relatively cheap. I was hoping I wouldn't encounter this problem. Now I'm kinda wishing I'd stuck with what I know and got some Pirelli Diablo Corsas instead.

What should I do, in your collective view? Take them back and have some new ones fitted? Ignore it? Is it possibly just a wheel balancing issue that is easily solved? I got it done at Road and Sport in Hamilton, and they test rode the bike before they gave it back to me. I'd have thought they would have picked up on this...

**Kwaka14** · 18th April 2007, 16:29

I had that with Azaro's when I first got them on the 12 and it was pretty unnerving for a little while however it dissapeared after about 1200ks, apparently it's to do with the tread pattern (varying spaces between the grooves) and as the rubber wears in a little bit it goes away, at least it definitely did with the Azaro's....

**Bnonn** · 18th April 2007, 16:50

Cool. I thought, looking at the treads, that maybe that was what was going on. Since it doesn't seem to be having much effect on anything, I'll leave it and see if it diminishes after riding a bit. That way I have some advice for others if they get a similar problem (:

**DougieNZ** · 18th April 2007, 16:54

I have just had a front fitted to my ST1300, and have found it to be excellent during the 500 odd k's i have done so far. I would say to persevere and report back.

Cheers

**vifferman** · 18th April 2007, 16:57

Check the pressure. I dunno what Storms are like (yet...) but my Azaro Sport front doesn't like being at less than 38 psi, and prefers 40 (!) due to the soft carcase.

**Bnonn** · 18th April 2007, 17:02

I was going to check the pressure on the way home. I've been putting 36/42 front/back in my old tires. I'll try 38/42 for the Storms (I ride two-up often anyway, so higher pressure is no problem as far as I'm concerned).

**Blackbird** · 18th April 2007, 18:03

Take it back and insist that they either fix it by better balancing or change the front tyre completely. Dave Easey from KB had his Storms fitted at Cycletreads in Barrys Pt Rd and it was so bad that they actually had to change his front tyre which fixed it completely. Both Bykey Cop's (fitted by Kerry at Motohaus) and mine shimmied slightly but not enough to take them back before we did our trip south as there wasn't enough time and it was only minor. Road and Sport fitted mine too at the end of February so I suggest you print the report that I posted on KB and take it along to them so they know the problem is wider than just you. I've already sent my report to Dold to relay to Avon to get feedback. I'll mention your problem to my contact there. I do urge you to stay with the Storms though as they are a fantastic tyre.

PS, my presures are 42 psi front and rear

**Bnonn** · 18th April 2007, 18:23

Thanks very much for the advice Blackbird. I will print out the report and give Road and Sport a call tomorrow, and book a time to have the tires looked at again over the weekend. If the shimmying isn't just caused by the tread, then I will definitely get the wheel rebalanced, and the tire(s) replaced if needbe. It seems odd that this would only affect Avon tires though. Surely poor balancing would cause shimmying on any tire? Yet I haven't heard of this problem other than with Avons.

**Blackbird** · 18th April 2007, 19:21

No worries. I think there's a bit more to it than normal dynamic balance issues - might be caused by a variation in sidewall thickness or something like that as most of the shimmying is over a relatively narrow speed range. This could possibly suggest a harmonic at work which gets damped by increasing centrifugal force as you get faster. Hitcher didn't experience any problem on his FJR1300 so perhaps front/rear weight bias and rake/trail also has some impact on the severity of the fault. As I said though, they're still the best tyre I've ever had on the 'bird. Wet weather grip is simply awesome.

Stay in touch, I'm determined to get to the bottom of this with Avon!

Geoff

**Hitcher** · 18th April 2007, 21:25

The Storms certainly lightened up the steering on my FJR, but I haven't experienced anything like "wobbling" as described above. I've done nearly 3,000km on mine now and love them to bits. Take this matter up with your tyre shop or Avon's New Zealand agent.

**Bnonn** · 18th April 2007, 21:29

Blackbird: the research I have done so far suggests that you are right. Bikes will naturally shimmy at certain speeds for the exact reason you state; only, usually this effect is virtually unnoticeable (just like the low-amplitude swaying that they do). With the Avons, something is causing the effect to be amplified, and it seems entirely likely to me that it has something to do with the sidewall density.

I'll definitely stay in touch (:

**Blackbird** · 19th April 2007, 12:49

Originally Posted by Bnonn

Blackbird: the research I have done so far suggests that you are right. Bikes will naturally shimmy at certain speeds for the exact reason you state; only, usually this effect is virtually unnoticeable (just like the low-amplitude swaying that they do). With the Avons, something is causing the effect to be amplified, and it seems entirely likely to me that it has something to do with the sidewall density.

I'll definitely stay in touch (:

I emailed Avon in the UK last night and got an immediate response (see below). Will keep you posted.

Hi Geoff,

Thanks for the feedback, we put a lot of time and effort into these tyres. I read the forum and realise information gets spread very quickly. Bad news still travels quicker than good!

I will investigate this shimmy issue.

Best regards,

Peter J McNally

M/C Technical Product Manager

**Bnonn** · 19th April 2007, 13:22

Cool. Be interesting to hear what he says. I was going to go into R&S today, but I'm sick, so sucks to that.

**thehollowmen** · 19th April 2007, 19:36

On the V-strom forums people were talking about this. Check your orientation arrow on the front tyre because apparently they get put on backwards an awful lot.

**Blackbird** · 19th April 2007, 19:47

Originally Posted by thehollowmen

On the V-strom forums people were talking about this. Check your orientation arrow on the front tyre because apparently they get put on backwards an awful lot.

Not on ours they didn't, but thanks for the thought. I'm an engineer (a sad bastard) and tend to be anal about checking the basics