Tyre Feathering
Discussion
So i have a bit of a mystery on my hands....
i noticed a couple weeks ago that my front tyres have some feathering happening on the outside edges, more so on the left than the right.
Having read up online ive had the alignment checked and although everything shows in the green they said there was a 11-12 degree difference between left and right (on the screen its called SAI if i remember correctly) however they can't see anything bent or broken and having had it checked at a garage they cannot see anything amiss either and they say it drives fine. I'm unsure where to go from here but id like to fix it before i munch my tyres up too badly.
i have also noticed that when on some of those really curvy sections that link a roads or motorways together that it will have a bit of a sound as the wheels rotate, similar to being on a rumble strip but not as violent or loud, this could just be the feathering creating this sound but i thought id mention it in case it helps.
The tyres are michellin xclimate 205/55/16 on a bmw 1 series coupe
i noticed a couple weeks ago that my front tyres have some feathering happening on the outside edges, more so on the left than the right.
Having read up online ive had the alignment checked and although everything shows in the green they said there was a 11-12 degree difference between left and right (on the screen its called SAI if i remember correctly) however they can't see anything bent or broken and having had it checked at a garage they cannot see anything amiss either and they say it drives fine. I'm unsure where to go from here but id like to fix it before i munch my tyres up too badly.
i have also noticed that when on some of those really curvy sections that link a roads or motorways together that it will have a bit of a sound as the wheels rotate, similar to being on a rumble strip but not as violent or loud, this could just be the feathering creating this sound but i thought id mention it in case it helps.
The tyres are michellin xclimate 205/55/16 on a bmw 1 series coupe
Nanook said:
457892345 said:
So i have a bit of a mystery on my hands....
i noticed a couple weeks ago that my front tyres have some feathering happening on the outside edges, more so on the left than the right.
Having read up online ive had the alignment checked and although everything shows in the green they said there was a 11-12 degree difference between left and right (on the screen its called SAI if i remember correctly) however they can't see anything bent or broken and having had it checked at a garage they cannot see anything amiss either and they say it drives fine.
i have also noticed that when on some of those really curvy sections that link a roads or motorways together that it will have a bit of a sound as the wheels rotate, similar to being on a rumble strip but not as violent or loud, this could just be the feathering creating this sound but i thought id mention it in case it helps.
The tyres are michellin xclimate 205/55/16 on a bmw 1 series coupe
Do you have a copy of the print out, from when you had the wheel alignment checked?i noticed a couple weeks ago that my front tyres have some feathering happening on the outside edges, more so on the left than the right.
Having read up online ive had the alignment checked and although everything shows in the green they said there was a 11-12 degree difference between left and right (on the screen its called SAI if i remember correctly) however they can't see anything bent or broken and having had it checked at a garage they cannot see anything amiss either and they say it drives fine.
i have also noticed that when on some of those really curvy sections that link a roads or motorways together that it will have a bit of a sound as the wheels rotate, similar to being on a rumble strip but not as violent or loud, this could just be the feathering creating this sound but i thought id mention it in case it helps.
The tyres are michellin xclimate 205/55/16 on a bmw 1 series coupe
As it wasn't out by 11 or 12 degrees. 11 or 12 minutes perhaps.
Are the tyre pressures good? Are the wheel bearings good?
Tyre pressures are checked every 2-3 weeks
Wheel bearing i was told is fine, as that was my first thought also, though im not sure how in depth they actually went to check that.
Nanook said:
Grab a protractor and a steel rule, and draw 2 lines converging at a point, one of them 11 degrees from being parallel with the other.
Think about what your car would be like if that's what your front wheels were doing all of the time!
It would be painfully, visibly, obvious if your alignment was that far out, with the naked eye, never mind some precision measuring equipment!
i'm just going off what they told me and what i saw on the screen. I can upload the picture of the screen tomorrow as ill have to get in touch with them to send me it.Think about what your car would be like if that's what your front wheels were doing all of the time!
It would be painfully, visibly, obvious if your alignment was that far out, with the naked eye, never mind some precision measuring equipment!
The guy said that he can't work out why its out by so much but he can't see anything wrong and when he got in contact with hunter they supposedly said that there shouldnt be such an issue so it must be something bent/broken but then when taking it to other places they said they can't see anything wrong.
The fact there is obvious feathering tells me something isnt right and this would seem to confirm it but if i cant get the problem found with inspections or alignment idk what else to do.
Edited by 457892345 on Monday 30th July 17:36
That printout does not show 11 degrees for anything. There are 360 degrees in a circle, and 60 minutes in a degree, so 1 minute is 1/21,600th of a circle.
The top half is before they adjusted things. The lower half is after.
Everything green is within spec.
The only thing red, outside spec, was the rear toe before they started.
Before - LH 0deg04min, RH 0deg29min - spec is 0d07 to 0d11. Add the two together for total toe - 0deg33min, compared to 0d14 to 0d22 spec. Thrust angle is the average of the two (is it tracking left, right or straight?) - 0d13 to one side, compared to spec of 0deg04 either side.
After - everything within spec, and thrust 0deg01min to one side.
SAI is Steering Axis Inclination - shown on there as Caster. It's grey because there's no spec for it, I'd guess.
The top half is before they adjusted things. The lower half is after.
Everything green is within spec.
The only thing red, outside spec, was the rear toe before they started.
Before - LH 0deg04min, RH 0deg29min - spec is 0d07 to 0d11. Add the two together for total toe - 0deg33min, compared to 0d14 to 0d22 spec. Thrust angle is the average of the two (is it tracking left, right or straight?) - 0d13 to one side, compared to spec of 0deg04 either side.
After - everything within spec, and thrust 0deg01min to one side.
SAI is Steering Axis Inclination - shown on there as Caster. It's grey because there's no spec for it, I'd guess.
TooMany2cvs said:
That printout does not show 11 degrees for anything. There are 360 degrees in a circle, and 60 minutes in a degree, so 1 minute is 1/21,600th of a circle.
The top half is before they adjusted things. The lower half is after.
Everything green is within spec.
The only thing red, outside spec, was the rear toe before they started.
Before - LH 0deg04min, RH 0deg29min - spec is 0d07 to 0d11. Add the two together for total toe - 0deg33min, compared to 0d14 to 0d22 spec. Thrust angle is the average of the two (is it tracking left, right or straight?) - 0d13 to one side, compared to spec of 0deg04 either side.
After - everything within spec, and thrust 0deg01min to one side.
SAI is Steering Axis Inclination - shown on there as Caster. It's grey because there's no spec for it, I'd guess.
The SAI being out by 11-12 degrees was show on their screen when the adjustment was done but i didnt take a picture of it, the printout they gave me doesnt display this info hence me mentioning this.The top half is before they adjusted things. The lower half is after.
Everything green is within spec.
The only thing red, outside spec, was the rear toe before they started.
Before - LH 0deg04min, RH 0deg29min - spec is 0d07 to 0d11. Add the two together for total toe - 0deg33min, compared to 0d14 to 0d22 spec. Thrust angle is the average of the two (is it tracking left, right or straight?) - 0d13 to one side, compared to spec of 0deg04 either side.
After - everything within spec, and thrust 0deg01min to one side.
SAI is Steering Axis Inclination - shown on there as Caster. It's grey because there's no spec for it, I'd guess.
I don't know any more than this. The guy simply showed me the figure, said it wasnt supposed to be that way and that he will call hunter as he can't see why it would be, after calling hunter he says must be a bend or something he can't see that is causing it so i take it to be inspected and they find no issues either.
Edited by 457892345 on Monday 30th July 17:47
Nanook said:
Can you show us pictures of this feathering?
The 'after' plots show you're running ever so slightly more neg camber on the tyre that you're not as concerned about, do you drive around a lot of roundabouts?
Honestly, if there was 12 degrees of anything going on, toe, camber, caster (when you have some lock on) , it would be immediately obvious to the naked eye.
I can, will update this post in 2minThe 'after' plots show you're running ever so slightly more neg camber on the tyre that you're not as concerned about, do you drive around a lot of roundabouts?
Honestly, if there was 12 degrees of anything going on, toe, camber, caster (when you have some lock on) , it would be immediately obvious to the naked eye.
The feathering happened before the alignment and was why i went to get it checked, but no, no crazy roundabout adventures to speak of.
I get what you are saying, all i can tell you is he said there is a 11-12 degree SAI difference, im not technically minded enough to be able to explain why or how or anything other than what i saw and was told by the person whos job it is to know.
Photo link because filesize:
https://imgur.com/a/dIXJv5J
Edited by 457892345 on Monday 30th July 17:59
TooMany2cvs said:
Just pause and think about what 11deg looks like...
Now think of the steering angle, the vertical axis that the steering pivots on, as being 11 degrees out...
Honestly i get what you are saying, i thought it was odd its somehow able to be in the green yet somehow out by 12 degrees SAI too, but i am not knowledgeable enough to call bullsNow think of the steering angle, the vertical axis that the steering pivots on, as being 11 degrees out...
t, quite simply i was told the SAI was out by 11-12 degrees and saw as much on the screen of the machine with all the other info and adjustments. I will prove as much with a photo of said screen tomorrow when the place re-opens.This is the information i have at the moment and i can only tell you what i know and have been told.
DRCAGE said:
Nothing to add except that my tyres are feathering too, I don't know why, and it's sending me loopy.
Didn't even know they could feather until it was pointed out to me tbh, Have you had your alignment checked too? Edited by 457892345 on Monday 30th July 18:07
TooMany2cvs said:
My money's on the chimp operating the tyre machine not actually knowing what a degree is, and simply thinking "11 thingies" = "11 degrees".
I saw it myself though, it was 11 degrees and some change. Here is a picture of an old alignment from kwik fit i have found. This shows exactly what i am trying to describe. All the adjustments are green yet a -22 degree SAI is shown, on the recent one i have it is -11-12 degree difference.https://imgur.com/CqY4BFf
I will add that this most recent alignment guy was shocked that kwik fit left a -22.54 SAI difference and said that it shouldnt be like that.
SlimJim16v said:
I think we have a winner 
I know all these accreditations and training these days aren't worth the paper their printed on but i'm sure that hunter at least go over that before certifying someone to work on cars. 
Edited by 457892345 on Monday 30th July 18:22
How long have you owned his car? How long do you suspect it's been like this?
I would assume it's been crashed at some point.
A quick check you can do is the measure how far the the wheel sits inside the arch on both sides. If one side sticks out more then there's your problem. The problem being that the chassis's bent.
I would assume it's been crashed at some point.
A quick check you can do is the measure how far the the wheel sits inside the arch on both sides. If one side sticks out more then there's your problem. The problem being that the chassis's bent.
hooblah said:
How long have you owned his car? How long do you suspect it's been like this?
I would assume it's been crashed at some point.
A quick check you can do is the measure how far the the wheel sits inside the arch on both sides. If one side sticks out more then there's your problem.
I did have a crash about a year or so ago but it was repaired through insurance via bmw elms. I will get this checked as it might be that..... I've had two incidents with kerbs to avoid cars pulling out on me too. I would have thought that the checks the guys at the garage did would have pulled this up though?I would assume it's been crashed at some point.
A quick check you can do is the measure how far the the wheel sits inside the arch on both sides. If one side sticks out more then there's your problem.
If it turns out they didnt repair it properly do i even have any recourse after all this time?
Upon reading about the symptoms for bent chassis i think this might just be it you know... Any ideas on what kind of machine the place i take it to needs to diagnose this for me?
Edited by 457892345 on Monday 30th July 18:32
457892345 said:
Didn't even know they could feather until it was pointed out to me tbh, Have you had your alignment checked too?
Same! I replaced my wheel bearings last November, go out for the smug test drive and the bloody noise is still there!I've had my tracking done twice, at two different places, one saying "it was well out mate".
New tyres start feathering, going crazy so replaced everything 2 weeks ago, the track rods were seized solid (as they are famous for doing) and honestly don't look like they've moved for years........
In all my research there really didn't seem to be any definite answers, some people even saying a new tyre or new tyre brand sorted it. But the consensus seems to be either alignment or a mix of alignment and a wonky bush/similar.
https://www.alignmycar.co.uk/sai-included-angle/
See above link, SAI is steering axis inclination and is angle between suspension strut and verticals so is typically 10-30 degrees.
I don’t know much about it but I would think it should be the same on both wheels on an axle.
See above link, SAI is steering axis inclination and is angle between suspension strut and verticals so is typically 10-30 degrees.
I don’t know much about it but I would think it should be the same on both wheels on an axle.
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