Forums > General Discussion   Shooting the breeze...

How make k's out of tyres

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Created by Crusoe 1 month ago, 29 Jun 2022
Crusoe
QLD, 1156 posts
29 Jun 2022 5:48AM
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Got the town car (Subaru Liberty) serviced recently and was told by the mechanic I needed new tyres. The guy was surprised they were the original tyres as I had done over 90,000 K's on them. Now I do slow down at roundabouts and corners but get back up to speed on the straights fairly promptly. Saw a car come around a roundabout the other day and the expression on the face of the driver was like someone riding the Whizzer at the show. I see a lot of people use 2 lane roundabouts as a way to move up one position in the Conga-Line of early morning traffic and often see 4x4 driven like high performance race cars and unable to stay within the painted lanes of the road. Just what is normal milage for a set of tyres. The tyres on my car a low profile and not cheap.

Tonz
486 posts
29 Jun 2022 6:45AM
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you gotta be doing something right, Id say that it a damn good run.
Tyres do depend on their quality (price) but also the way they are treated, I would guess your car is also very well looked after.
What brand?

Mark _australia
WA, 21603 posts
29 Jun 2022 8:52AM
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Constant 4WD does wear more evenly of course. Then yeah not throwing it through corners :) but you said town car so I gather it doesn't see a lot of corners......?

90K is exceptional on an OEM set, usually the stuff they fit at the factory is made special to be quiet and grippy and plush ride etc - sells cars but wears faster

My Liberty wagon had 60K from normal tyres and about 40K from a performance set so reckon you've done awesome

Inflation of course too, only a few psi difference between uneven wear and just nice

Carantoc
WA, 5835 posts
29 Jun 2022 9:14AM
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Rotate, balance and tracking.

Rotate is easy, do it yourself just takes and hour or so. Once every 8 to 10 weeks makes a big difference.
Balance and tracking bit harder unless you have some fancy stuff in your garage, so just get it done every service by somebody else.

Got 80,000km from a set on Goodyear on a 4WD, including at the end Cape Leuwin to Cape York and return via Birdsville track and old coach road across the Nullabor. Not much left of them and probanly stopped being legal somewhere in outback Queensland, but I thought it was good mileage

Flip side used to get about 4 weeks from a rear on my motorbike every summer. Front would last a year, Bridgestone on rear over winter would last 6 months, Pirelli on the rear over summer less than 6 weeks. Loved the stickiness of the Pirelli though.

Used to get about 5,000km on rear and 8,000km on fronts on Bridgestone V-Steel light truck tyres on a Landcruiser running up and down the BHP rail line. No other tyre came close to that.

Ian K
WA, 3984 posts
29 Jun 2022 9:49AM
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Taxi drivers had been known to store them for a year or so before fitting them. Lasted longer, they didn't worry about grip back then. Maybe your car got fitted with old stock? How old were they when retired? They reckon the rubber has gone so hard after 5 years they need replacing no matter what.

Have you noticed that old boards don't ding as easily? Probably same sort of thing going on.

Ian K
WA, 3984 posts
29 Jun 2022 11:08AM
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Select to expand quote
Carantoc said..
Rotate, balance and tracking.


Tracking? Had an Alfasud once. The manual said if there was a tracking or tyre wear problem to " inspect the suspension and replace the bent components". Thinking about it, it made sense. the strut towers were braced hard up against the firewall and Macpherson struts are a pretty well triangulated system.

Years later a family member bounced a Kia over a high gutter at cruising speed, smashing a front wheel. The spare, when fitted, was obviously not centred in the wheel well. Crawling underneath I could see the bent component. I asked the mechanic as to how bad the alignment was after the bent bit was replaced. He said. "We checked it but it was all OK didn't need any adjustment".


But I'm sure most garages would be happy to charge for an alignment of a FWD, Macpherson strut front end.

gavnwend
NSW, 1230 posts
29 Jun 2022 1:50PM
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The right tyre pressure is the secret. Your steering wheel should be centre.(alignment). Soft compound rubber is totally useless.

damned67
324 posts
29 Jun 2022 12:04PM
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I do a LOT of highway driving. My Golf now has about 180k on it, and I just put the second set of replacements on the car 5k ago at the last service - and I'm 100% the tyres were an up-sell. Probably would have been close by the next service though. Rather be safe than sorry.
but yeah, I get 80-90k out of a set, and my first replacement set would have got an easy 15k more than the OEMs. As said, pressure, rotation and alignment make all the difference.

Craig66
NSW, 2304 posts
29 Jun 2022 2:07PM
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Put a set of BFGoodrich A/T on 80 series cruser years ago and did central aus trip towing camper, some thing like 6000km of gravel, (most at a quick pace) out through cameron corner, up to birdsville, around ayres rock, kings canyon etc.
Most people said run low presser on the gravel but i run 65psi to reduce risk of sidewall puncher.
The tread was chewed up heaps but no punchers.
The tyers lasted foreever/ years but they got so hard but was tricky (fun) to drive in the wet.

Kamikuza
QLD, 6390 posts
29 Jun 2022 8:44PM
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Used to get 2,000 to 3,000 km out of the bike tires, but all I ever did on that bike was ride 20 minutes to the mountain then spend 3 hours chasing up and down the twisty bits.

Get a lot more out of the car tires, but not 90,000 km! Well done... Think I get about 60k out of a set. Put 200,000 km on the Voxy and was about due for the 4th set of tires. Then it blew up :D

Mind you, I buy whatever sets are cheap -- last set of 4 cost $150 off Amazon and $50 fitting/balance...

Harrow
NSW, 4141 posts
30 Jun 2022 10:29AM
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I get about 30,000 a set. Not great, but it's a question of replacing the tyres every second year, or getting a weekly wheel alignment as the members of my family insist on slamming the gutter every time they park.

Ian K
WA, 3984 posts
30 Jun 2022 9:36AM
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Harrow said..
I get about 30,000 a set. Not great, but it's a question of replacing the tyres every second year, or getting a weekly wheel alignment as the members of my family insist on slamming the gutter every time they park.



Which component of the suspension system do you think exceeds its elastic limit when they biff the gutter?


Elastic limit
"the maximum extent to which a solid may be stretched without permanent alteration of size or shape."

Could be another of their unknown driving habits that trashes tyres in 30k.

Harrow
NSW, 4141 posts
30 Jun 2022 12:34PM
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Ian K said..
Could be another of their unknown driving habits that trashes tyres in 30k.

No idea, but the way the car goes straight one week and then is pulling to one side or the other the next week, along with the grazes on the side wall and increasingly scraped rims suggests to me the kerb hitting is a contributor.

The apparent need to hit the brakes every time a bird flies overhead or a branch on the side of the road swings in the breeze doesn't help. Going through brake pads like they are candy.

Ian K
WA, 3984 posts
30 Jun 2022 11:28AM
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Maybe your rubbery suspension bushes are worn, out of round and randomly rotating in the mounting?

As a geologist once told me. " There's a reason for everything"

Carantoc
WA, 5835 posts
30 Jun 2022 11:37AM
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Ian K said..
Which component of the suspension system do you think exceeds its elastic limit when they biff the gutter?


You seem to be on a theory that once alignment is done it can never be undone, except when something is bent beyond its capacity to safely function.

Not sure I agree, either with that in practice or in theory.

There are a lot of dynamically acting and non-rigid components in the steering and suspension system. Many are replaceable components designed to wear and be replaced. That process of wearing changes the geometry of the whole system long before the specific component needs replacing.

There's lots of mechanisms and lever ratios going on where a single 1mm in a strut sag might be several degrees at a wheel. And alignment issues can occur with less than 0.5 degree in toe-in or caster.

Add in the fact that much of the system is designed with adjustability as well - and mainly mechanical adjusters (threaded couplings etc) that have the potential to move and adjust with impacts. Rubber bushes don't have a single to the 0.00001mm seating locations.

And then even the tyres themselves are not going to be 100% uniform. As the tyre wears it is going to change the dynamics of the whole thing.

If it idea is that all that normal wear is not going to be noticeable, I am not so sure in practice. All my experience indicates that if you get the tracking and alignment right it doesn't stay right forever.





Carantoc
WA, 5835 posts
30 Jun 2022 11:53AM
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..and the last Subaru I had (4wd wagon like the Brumby, don't recall the model name now) there was lots of suspension easy adjustable bits on them, designed to be adjusted by the user not a mechanic.

Ride height was a big bolt under the back seat and two nuts on the top of each front strut. If you wound the suspension up or down you were also supposed to then set the camber. This was via a cammed worm gear behind the front wheels somewhere.

Maybe some cheap throw-way modern vehicles are 100% fixed and have no adjustability in anything. Bushing worn ? replace the entire strut. Spring sagging ? new front end required, Alignment is out ?? the only options are to replace a part or replace the vehicle.

I dunno. Maybe electric cars are like that. Throw away product for the enviro conscious millennial who can't workout how to use a spanner ?





Google tells me for a Subaru Liberty (vehicle in original post) :

FRONT WHEEL TOE-IN:
Toe-in: Inspection value 0 +/-3 mm (0.00 +/-0.12 in)
Toe-in: Adjustment value 0 +/-2 mm (0.00 +/-0.08 in)
FRONT CAMBER:
Camber Inspection value 0.00'+/-45' (difference between RH and LH 45' or less)
Camber Adjustment value 0.00 +/-30' (difference between RH and LH 45' or less)
REAR WHEEL TOE-IN:
Toe-in: Inspection value 3 +/-3 mm (0.12 +/-0.12 in)
Toe-in: Adjustment value 3 +/-2 mm (0.12 +/-0.08 in)
REAR CAMBER:
-1deg00' Camber (tolerance: +/-45'. Difference between RH and LH: 45' or less)

1/2 or degree 2mm isn't much to be out of tolerance.

Ian K
WA, 3984 posts
30 Jun 2022 4:19PM
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Select to expand quote
Carantoc said..

Ian K said..
Which component of the suspension system do you think exceeds its elastic limit when they biff the gutter?



That process of wearing changes the geometry of the whole system long before the specific component needs replacing.

There's lots of mechanisms and lever ratios going on where a single 1mm in a strut sag might be several degrees at a wheel. And alignment issues can occur with less than 0.5 degree in toe-in or caster.






A hypothesis rather than a theory, and I had a car repaired at Pedders once that came back scarily unsafe to drive on undulating country roads. The local servo fixed it up by being more careful with the alignment. Why take chances with an apprentice mechanic unless you have to?.

Can a worn ball joint or rubber bush be compensated for with a wheel alignment? The suspension is designed to maintain toe in reasonably well under compression. That's its main job after all. I doubt a 1mm static spring sag when unladen will cause much change to alignment.
I'd only get a wheel alignment after a big impact. Normal gutter bouncing at parking speeds. Don't bother.

Harrow
NSW, 4141 posts
1 Jul 2022 6:18AM
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Select to expand quote
Ian K said..
Maybe your rubbery suspension bushes are worn, out of round and randomly rotating in the mounting?

As a geologist once told me. " There's a reason for everything"

440,000 on the clock. Maybe?



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Forums > General Discussion   Shooting the breeze...


"How make k's out of tyres" started by Crusoe