Tyres not round (No, really!!)

Technical Area Wheels, Tyres & Brakes
2

 Recently put my summer tyres back on (and alignment checked at the same time), and have noticed what sounds like a differential-failing noise from the rear (sort of hum with a regular change of pitch, related to car speed but disappears at higher speed). A bit scary!

So I jacked up each corner in turn and turned the wheels by hand. No strange noises as far as I could tell, BUT the tyres on the front (which are easier to spin) both have a sort of flat spot i.e. they are not round. It’s difficult to tell if the rears are the same 'cos the drag from the diff stops the wheels turning freely enough.

So I’ve jut put the Winter rears back on, and unless its my imagination the regular noise has subsided (but there’s a lot of wind noise out there drowing-out everything else!). I’ll swop them back and forth a couple of times in the next week or so and see if there’s definitely a difference, and maybe get them checked on a tyre balancer for roundness.

The suspect tyres are GSD3, stamped “Made in Germany” with about 6000 miles use (ie last summer, what there was of it). In storage they are laid on thier side, so any flat spots should have been avoided. I don’t think they are out-of-balance since I’m not getting any vibration, which is surprising.

So while I’m sorting this out, I’m assuming I’ll need to put something on the car that stays round! (Shame really, the grip on these in the dry is phenominal, albeit with a bit of tramlining until they warm up)

So the obvious question is - all those people out there that put thier favourite tyres on - be they Toyo, Uniroyal or whatever - could you provide feedback on whether they stay round? Context - I’m not interested in out-and-out performance so much as being able to drive distances comfortably, motorway and non-motorway, in my 1.8 MK3. And a regular noise such as this is very discomforting! The WRG2 are excellent at that, but I suspect if I keep them on the in summer they will wear out fast, and they definitely make more noise in the warmer weather!

Cheers - Richard

 

3

It might be your wheels if they are aftermarket ones. I had this happen to me once and it turned out that the plastic hub spacer ring needed for aftermarket wheels was missing. This meant that the wheels did not seat on the hub perfectly centrally. After several visits to two different garages it took someone actually spinning the wheel while the car was on a ramp to notice that it was actually moving around.

4

 It sounds like the tyres are old. Your comment about them warming up leads me to think they have age hardened. It should be possible to see the age from the codes on the side

 

This one is made in 51st week of 07

5

Ta folks but all tyres are less than 3 years old and are fitted to the original MX5 wheels which are perfectly OK! But there are lots of posts about the GSD3’s causing problems.

Any info on the alternatives “going off” like (OR NOT AS THE CASE MAY BE!) this would be welcome …

6

 

I once had this problem years ago with Dunlop SP tyres on a Rover.  They simply went ‘out of round’.   Tyres were sent back to Dunlop after 4,000 miles of wear and they offered 20% refund on a new set.  This increased to 75% after a ‘few words’!  I replaced them with Avon if I recall.  If the tyres are misshapen there is no alternative but to buy a new set, but investigate returning them as faulty to the manufacturer with a view to a refund.

Regards  Geoff Peace.

7

We have replaced tyres that cause a huming noise very similiar to a wheel bearing.  The tread blocks dont wear flat and hum.  The noise is quite like a 4x4 off road landrover tyre.  I don’t know why it happens but it’s often low profile tyres with fatter tread blocks. It’s more common than you would think. 

8

 Years ago I had a tyre grow a large lump on the tread, they were’nt retreads. It appeared it had delaminated, allowing air into the outer layer and inflating it beyond the bracing plies.

 I have known an HGV develop flat spots due to standing still for days but they recovered when warmed up in a few miles.

9

 Hi Nedski

You are right about the noise !!!

My mate drives a Mazda 3 and he thought that the rear bearing was making a humming noise so he went to Mazda and sure enough it was his rear tyres !!!

The noise come after he rotated the tyres, after he put them back to the front of the car the noise was gone.

I think it was down to tyre wear and with the car being much lighter at the rear this allowed  the noise to happen.

Just a thought.

Regards

Jeff

10

 

 Did you not think to put the rears on the front and spin them that way?

If you have the car on stands you can start the engine and let that turn them.

Don’t discount that weights have fallen of and the dynamic balance is out.

11

 

 

Sorry to disagree, but this is absolutely wrong. The Spigot ring is just an aid to fitting the wheel and particularly so when you have wheel studs rather than bolts. While some wheels, trucks for instance have a bore than the wheel centers on and the bolts then hold the wheel, most cars do not have this. It is the conical nut that seats and locates the wheel. The weight and trueness of the wheel is not held on a plastic spigot ring. You don’t need them.

12

 

Hi NickD

Is it possible for this to happen on a front wheel, without getting any vibration through the steering?

 

13

 Well, after a few days messing about with bits of chalk and swopping wheels around, I can say that the GSD3 tyres that I have show the following:-

  1. The ones I had on the rear were causing a noise similar to a bearing or differentialon the way out (a sort of rythmic hum). I know this because when I put the Winter tyres back onto the rear, I stopped worrying about the cost of a new diff!

  2. The GSD3 tyres when inflated to 29 or 30 psi on the MK3 will develop a flat spot when the car is parked overnight

  3. This flat spot will disappear if you store the wheels on their side for a couple of days

  4. This flat spot will disappear if you drive the car for about 10 miles, including a bit of dual cabbageway (and the steering will improve as well!)

NB the Summer tyres in question were the ones I used last summer, with none of the problems I am now having. Two of them were in use the summer before (see if you can guess which ones!).

I’ll let you know in a couple of days if upping the pressures a bit works.

I was going to attach a PDF of my detailed finding for the geeks among you, but can’t see how to do it. So I’ve attempted to paste the content of my Word document into this post below here :-

THE PROBLEM

  • 1) Noise from rear, sounds like differential or wheel bearing- hum with a regular pulse (rhythmic hum). Seems to be at wheel speed. Does not seem to get worse under load. Not apparent at higher speeds (drowned out?). Seems to come from left side of car. Turning up radio to drown-out!
  • 2) Unsteadiness at front end
 

PERCEPTIONS

Seems to coincide with fitting of summer tyres. These were fitted as per normal practice rotated front-rear (but not side-side)

Some internet research suggested the GSD3’s can cause such a noise.

 

INVESTIGATIONS

9/5/2013 (Thurs)

Jacked up each rear wheel in turn, rotated it and tried to see if there were any funny noises or tyres distorted.

Any funny noise/looseness etc.?  - no.

Any tyre distortion - Seemed to be a little, but could not tell - drag from transmission meant I couldn’t keep still while turning them!

Replaced both rears with the Winters to see if any difference.

Stored rears on side.

Checked  the front wheels - both tyres seemed to be slightly distorted.

All rims OK, no sidewall bulges etc.

TEST DRIVE - in use the rhythmic humming was no longer evident. Subsequent trip out revealed it seemed to have gone away, although blustery windy weather might have drowned it out. Blustery, windy weather with high winds.

11/5/2013 (Sat)

Drove about 100 miles or so, no evidence of rhythmic hum from rear.

12/5/2013 c11:00 am (Sun)

Jacked each front tyre up in turn, and used steady piece of chalk to check for distortion. Both fronts showed "flat spots"  around 20% of circumference.  In both cases this was the part of the tyre that had been in contact with the ground overnight - from about 6pm - 11am the following day.  Tread depth same on the depressed section of tyre and the opposite side of the tyre.

Move the rears out of store and onto front. Both perfectly round!

Left them on the car.

Stored fronts on side.

TEST DRIVE

Weather much calmer, dry and mild. Seemed a lot steadier/steering improved (although it is possible that windy conditions over the previous few days may have been a factor). Still no evidence of rhythmic  hum from rear.

Later that afternoon - turned colder and wet. On uneven surfaces you could tell! At one point also thought I heard the rhythmic  hum, but more faintly, and from the front.

13/05/2013 11:15 am (Mon)

Checked front tyres - now have flat spots at the bottom (c 20% of circumference of tyre) after being parked for c 17 hours. (NB these were previously on the rear and were brought out of store and onto the front on 12/5)

Went for short spin (about 8-10 miles), weather reasonably warm.

                Left front - flat spot almost disappeared

                Right front - flat spot has disappeared

Still no evidence of rhythmic hum - the Winter tyres seem to have done the trick!

14/05/2013 10:30 am (Tue)

Checked stored tyres - now perfectly round! These came off the front a couple of days ago, and have lost theier flat spot in store.

Put them on the back and went for a test drive. Noise has not re-appeared .

Winters back into store.

CONCLUSIONS SO FAR

  • 1) The rear tyres were causing the rhythmic humming noise, since this has gone away now the Winter tyres are on the back..
  • 2) The front tyres were causing the instability, since this was much reduced when the rear tyres replaced them on the 12th.
  • 3) The flat spot has probably always been occurring, and probably is not the cause of the rhythmic hum (since the tyres on the front from 12/5 are the ones that were on the back when the noise occurred).
  • 4) The flat spot will disappear if
  • a. The tyres are stored on their side for a couple of days
  • b. You go for a drive and warm them up.
 

OTHER OBSERVATIONS.

                Interesting coincidence that both the front tyre flat spots were at the ground contact point!

The two front tyres were the oldest - date 0308 on the left front, 5108 on the right front.

                The two rear tyres were dated 3711 and 3911.

                30 PSI on the original rears, 29 on the original fronts

NEXT

Action Status
Check fronts after standing overnight to see if flat spot developed. Done 13/5,see above.

 
Check the stored tyres after a couple of days to see if flat spot has gone away! Done 14/5, see above

 
Put the stored tyres on the rear to see if rythmic humming noise re-appears. Done 14/5, see above

 
Up pressures a couple of pounds and see if the flat-spotting still occurs. Upped 14/5, need to check after overnight stand
   

 

Checks/Actions 12/5/2013 Dated   Tread  
Left Front 0309 On car, flat spot found, 20% touching ground c 5mm all round Moved into store 12/5
Right Front 5108 On car, flat spot found, 20% touching ground <6mm all round Moved into store 12/5
Left Rear 3911? No flat spot when removed from storage <7mm all round Moved onto LF 12/5 (This is where it was last year)
Right Rear 3711 No flat spot when removed from storage <7mm all round Moved onto RF 12/5 (This is where it was last year)
14

 What you are describing is not uncommon. Rubber has a memory and with the higher speed speed rated tyres they tend to be stiffer. The temperature variations, you park while it is relatively warm, the tyre has heat in if from use, then everything cools down over night, and particularly the road stays cold, and the rubber retains the flat from where it was standing.

Usually this will disappear as you say, within a few miles as the tyre flexes and heat softens the rubber.

It is however possible for these to remain if the car has stood for a very long time. The fact this is happening every day now might suggest it is time for some new rubber as these sound like they are getting quite hard.

15

 Thanks for that Nick - I thought I’d found something horribly wrong. These tyres have always felt a bit “hard” - if you grasp a bit of the trea and try to move it it doesn’t shift - and neither did the tread blocks on the Advans. But you can just about move the tread blocks on my Winter tyres (there’s more to grab hold of, over 9mm of tread when new!)

Not happy about changing the tyres, given their ages - 2of them are only 18 months old, and the oldest (about 4.5 years) is no worse. So if they are going off it would mean that 2 summers use is all we can expect to get Confused! Too expensive for me …

Maybe if they last me the summer I’ll start looking for some decent V or W rated all-season tyres (My Nokians are only H rated) if such a thing exists (any ideas anyone, or have Vredestien got the only ones in our size?) - so if they go off after a couple of years at least I’ll get 2 full years use out of them instead of two summer’s worth … At least all-season wear shouldn’t leave me with unpleasant handling on those cold, damp spring and autumn days.

Interstingly I’ve had 3 Winters out of the Nokians (about 14,000 miles worth) and they are hardly worn, and don’t give me any problems.

Ho hum …

 

16

 Your winter tyres will move more as they are designed to do so. You will see the thread is stiped with lots of little breaks in the larger tread pattern.

When I say it is not uncommon, I mean it does happen, however it is not that common. It does seem to be a problem inherent in the GDS3 tyre. 

My Mrs’s has bought a 53 plate Sport tonight. It has sat since at least February and the Accelera budget tyres made in 09 were quite round, even though they had zero grip in the rain. Tonight I kitted some new Kumho tyres and again I don’t expect any issue with roundness. 

17

 

Methinks a polite letter to Goodyear is in order . I’ll post up the results here, if any. And revise the review of the GSD3’s I posted on the mytyres review site as well …

18

 

Polite, yes, but firm.  The difference between being aggressive and being asssertive.  My advice, for what it is worth, is do not give them any wriggling room!

Regards Geoff Peace.

19

Part of response from Goodyears technical dept - the rest is about procedures for submitting the tyres for testing, and advice on storage (which matches my own procedure!) 

"It is not normal to have flat spots appearing as you describe . A flat spot normally occurs when a vehicle has been standing for several months and the tyres have neither been over inflated or rotated . When used heat in the tyre would help the casing straighten . "

Clearly my first priority is to cease using the GSD3’s (which I have!), then replace them with something else, then see if I can get something back from Goodyear.

Not a nice position to be in!

An interesting question yesterday from my wife was (“What would have happened if you hadn’t got a set of winter tyres to play with”). I think the answer is illustrated by going to this link http://www.tyrereviews.co.uk/Tyre/Goodyear/Eagle-F1-GSD3.htm and looking at the BMW525 owner’s experience, plus posts on the Mondeo ST and Subaru forums.

Now all I have to do is figure out how to carry 4 wheels down to the tyre dealer - in an MX5!

Addendum - Well they’ve gone back to the dealer for the test process to be started - along with all the relevant forms filled in (Goodyear sent me this link http://www.btmauk.com/page/useful-information/complaint-procedure/  ). And a set of Toyo T1-R’s on order (Needed for my trip to Cornwall at the weekend, don’t want to do this on H-rated winter rubber), they seem popular for the MX5 so I hope I haven’t dropped another brick, it’s getting a tad expensive!

20

 Well, I’ve got the results of the test process.

Against each and every tyre it says “Our inspection confirms the above tyre to be within manufacturing specification”

Ho hum.Sad