Can a tyre with slight flat spots smooth out over time?





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  1. #1
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    Default Can a tyre with slight flat spots smooth out over time?

    So I learnt something recently, if you don't rotate tyres, especially the back ones you can develop flat spots or what seems to be called mild scalloping or cupping.

    It happens especially on tyres with long tread lugs, so probably not so much on off road bias tyres with lots of space between lugs to shed mud. Mainly on vehicles that don't have a heavy load on the back, I suppose like a light passenger vehicle with only ever one person in it or an unloaded bakkie.

    I got a vehicle recently and there was slight road noise at the rear, wasn't loud enough for wheel bearing but I thought that was a possibility. The front tyres were noticeably more worn than the rear so I took them to be balanced and rotated, while it was up on the lift I checked the wheel bearing, all seemed fine but the tyre guys picked up slight flat spots on the rears.

    They immediately gunned for 2 new rear shocks and tyres. Many forums said no rotation causes it, which the difference in wear bears out and how mild the flat spots are, they are only in the centre of the tyre and it's not easy to feel them but they are there.

    Mounted on the front the flat spotted tyres make a mild noise, annoying but that's about it, absolutely no shaking or weird road handling even at highway speeds.

    So my question is has anyone experienced this or something similar and had the flat spots wear out?

  2. #2
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    Default Re: Can a tyre with slight flat spots smooth out over time?

    Unfortunately not.

    Wear will be even over the total area.
    Life of the tyre is now limited to the depth of the flat spots.
    Johan Maree
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  4. #3
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    Default Re: Can a tyre with slight flat spots smooth out over time?

    Quote Originally Posted by JohanMaree View Post
    Unfortunately not.

    Wear will be even over the total area.
    Life of the tyre is now limited to the depth of the flat spots.
    Why would the high spots not gradually wear down being at the front weighted down by the engine and now also being on the driven wheels?

    The tread still has plenty of depth and the flat spots are tiny relative to the remaining tread.
    Last edited by Skylark; 2020/08/07 at 12:41 PM.

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    Default Re: Can a tyre with slight flat spots smooth out over time?

    The cars that were built PQ24 (polo 9n etc) were especially prone to this.
    Also called sawtooth wear on the rear tyres.

    Rotating is the only way to overcome this.

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    Default Re: Can a tyre with slight flat spots smooth out over time?

    But - they never go away once you have them.
    Gavin Pike

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    Default Re: Can a tyre with slight flat spots smooth out over time?

    They actually get worse with time.

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    Default Re: Can a tyre with slight flat spots smooth out over time?

    Quote Originally Posted by gavpike View Post
    But - they never go away once you have them.
    Quote Originally Posted by Andrew Leigh View Post
    They actually get worse with time.
    That sucks, 2 other wise good tyres in the bin then. It is bloody annoying listening to the flapping noise it creates, I had it all day today. It's on a newly purchased 2hnd vehicle and it's hard to enjoy it like that.

    Via Google I found a guy that said he sanded his treads flat again by hand with sandpaper and a flat block and it worked, time to get stuck in

    Seems in the USA they actually have a service for shaving tyres to remove uneven wear but even if available in SA I doubt it'll truly be worth it. A new tyre is around R900 each so sinking what will probably be around R200+ per tyre into old tyres wouldn't make a lot of sense.

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    Default Re: Can a tyre with slight flat spots smooth out over time?

    if the flat spots are in the middle of the tyre, increase the tyre pressures a bit by like 1 bar over normal and see what happens, then after a month of driving like that drop to normal, and see its worth playing with tyre pressure - the tyres "are headed for the bin anyway" so if you get another month or two out of them and learn a bit its well worth it

    the tyre shaving process is really crude - I have done it for race tyres, you literally take a brand new tyre, spinning on either a wheel balancing machine or on the driven hub of the vehicle but not too fast on a lift and a carefully wielded angle grinder with a flapper wheel and you literally shave off the top layer or two of tread, think of a lathe but much much cruder, we used to do it to get the 1mm wear indicator to avoid the tread squirm on track and to have a tyre with zero heat cycles, so we ended up with softer rubber, the principle will be the same on your setup, this was back when the race series required the cars to be compliant with road legal tyres, IT MAKES A MESS OF NOTE AND SMELLS HORRENDOUS !!!!

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    Default Re: Can a tyre with slight flat spots smooth out over time?

    Quote Originally Posted by Skylark View Post
    That sucks, 2 other wise good tyres in the bin then. It is bloody annoying listening to the flapping noise it creates, I had it all day today. It's on a newly purchased 2hnd vehicle and it's hard to enjoy it like that.

    Via Google I found a guy that said he sanded his treads flat again by hand with sandpaper and a flat block and it worked, time to get stuck in

    Seems in the USA they actually have a service for shaving tyres to remove uneven wear but even if available in SA I doubt it'll truly be worth it. A new tyre is around R900 each so sinking what will probably be around R200+ per tyre into old tyres wouldn't make a lot of sense.
    Put the music louder (aka, turn the radio up)?

    Anyway, maybe have the tyres put back on the back (new tyres up front if the old ones went to the back and are kind of low) so you can still get good from of them?

    Or maybe sell them to someone who would have use for them? How old are they? Are they size 175/65R14?
    Last edited by supersunbird; 2020/08/08 at 09:25 AM.

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    Default Re: Can a tyre with slight flat spots smooth out over time?

    I've never ever had that. Could it not also happen to old tyres? In which case, replacement should be the solution anyway?
    Jakes Louw
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    Default Re: Can a tyre with slight flat spots smooth out over time?

    Every Fortuner (4 now) I have had all fitted with Bridgestone's from the factory have flat spotted.

    This is evidenced at the first tyre rotation (10 000km's). The minute the rears come to the front you feel it as tyre feedback is more direct. As stated I have had it on all 4 Fortuners. Reecently on my 4l I rotated at first service (15 000km's) and problems, that irritating bounce is back. I believe that the the problem originates at the rear, when the good front tyres are moved to the rear these become flat spotted as well and there is no way back.

    Many years ago I had my tyres ground on a small passenger car. There is a machine that takes one tyre at a time and has contra rotating blades that grind off the unevenness. Kinda like a tyre lathe. It worked. I am sure these still exist in some shops.
    Last edited by Andrew Leigh; 2020/08/08 at 09:44 AM.

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    Default Re: Can a tyre with slight flat spots smooth out over time?

    Pretend they mud terrains

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    Default Re: Can a tyre with slight flat spots smooth out over time?

    Quote Originally Posted by 3bar View Post
    if the flat spots are in the middle of the tyre, increase the tyre pressures a bit by like 1 bar over normal and see what happens, then after a month of driving like that drop to normal, and see its worth playing with tyre pressure - the tyres "are headed for the bin anyway" so if you get another month or two out of them and learn a bit its well worth it

    the tyre shaving process is really crude - I have done it for race tyres, you literally take a brand new tyre, spinning on either a wheel balancing machine or on the driven hub of the vehicle but not too fast on a lift and a carefully wielded angle grinder with a flapper wheel and you literally shave off the top layer or two of tread, think of a lathe but much much cruder, we used to do it to get the 1mm wear indicator to avoid the tread squirm on track and to have a tyre with zero heat cycles, so we ended up with softer rubber, the principle will be the same on your setup, this was back when the race series required the cars to be compliant with road legal tyres, IT MAKES A MESS OF NOTE AND SMELLS HORRENDOUS !!!!
    I tried various pressure from 1.5bar to the max rated 3.6bar, the noise continued at all pressures and the harder the tyre the more the noise.
    I'll make a call or 2 about the tyre shaving maybe it'll be an option, thanks for the heads up on the smell and mess

    Quote Originally Posted by supersunbird View Post
    Put the music louder (aka, turn the radio up)?

    Anyway, maybe have the tyres put back on the back (new tyres up front if the old ones went to the back and are kind of low) so you can still get good from of them?

    Or maybe sell them to someone who would have use for them? How old are they? Are they size 175/65R14?
    Not sure on the age, they don't look very new, they are 15" passenger tyres. They still made noise on the back just less, if I can't get them sorted I'll have to replace them because I can't take the noise, especially not for months on end.

    Quote Originally Posted by sparewheel View Post
    Pretend they mud terrains
    That is exactly what they like, the only problem is I won't be in a monster truck feeling like a boss enjoying the roar of my massive tyres, I'll be in a little urban run around wanting to enjoy the refinement and lack of noise.

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    Default Re: Can a tyre with slight flat spots smooth out over time?

    I agree with the above
    There is one thing you can try,Find a company doing retreads on passenger cars.
    Years ago they use to have skimming equipment to round out retreads.By skimming the tyre you will have the same result as sanding with the advantage of it running true
    Disadvantage obviously losing quite some tread
    Also remember some brands are more prone to flat spots and feathering
    Worn shocks also aggravate the problem
    I hope you come right

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    Default Re: Can a tyre with slight flat spots smooth out over time?

    Quote Originally Posted by dawid de lange View Post
    Worn shocks also aggravate the problem.
    And flat spots can accelerate shock wear.

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    Default Re: Can a tyre with slight flat spots smooth out over time?

    Cross rotate and drive it for 2000km.

    I had the same issue and after doing the above the hum is gone and the tyres are perfect and quiet.

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    Default Re: Can a tyre with slight flat spots smooth out over time?

    I thought cross rotating was a big no no as tyre's were directional?

    Or is it ok for a short period?
    Last edited by Andrew Leigh; 2020/08/10 at 12:54 PM. Reason: spelling

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    Default Re: Can a tyre with slight flat spots smooth out over time?

    Quote Originally Posted by Andrew Leigh View Post
    I thought cross rotating was a big no no as tyre's were directional?

    Or is it ok for a short period?

    Did it with Hankook AT's

    Worked well.

    Still alive to tell the tale.

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    Default Re: Can a tyre with slight flat spots smooth out over time?

    Quote Originally Posted by Kaboef View Post
    Cross rotate and drive it for 2000km.

    I had the same issue and after doing the above the hum is gone and the tyres are perfect and quiet.
    By cross rotate you mean RR to LF and so on?

    I don't think I could take 2000km of this noise though and it's on an automatic vehicle so I'm a little worried it may potentially damage something in the gearbox or elsewhere.

    But that being said from the perspective of the suspension and gearbox the uneven wear on the tyres cant be worse than driving on dirt roads or corrugations?

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    Default Re: Can a tyre with slight flat spots smooth out over time?

    Yes. LR to RF, and so on.

    I got the advice from a very respectable indy mechanic. Lots of guys know him.

    I also thought my wheel bearings were shot, but he said it's the tyres that were feathered, and told me to cross rotate.

    I say 2000km, but to me honest my tyres fixed themselves much quicker than that.

    The hum was gone and I am still driving the same tyres, 20,000km later.

    They are now shot, having given me 90,000km.

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