New tyres

[cajal]

[quote user="EuroTrash"]I thought that tracking/wheel alignment corrects the caster angle ie the toe-in toe-out. You make it sound as if it's two different things?[/quote]

Me too.

[richard51]

Another tyre question from ignorance. Is there an issue with uneven tyre wear when a right hand drive car (UK) is used for some considerable miles (km) on other camber roads on the continent?

[Mr Wiggy]

Wheel alignments ensure that all four wheels are consistent with each other and are optimized for maximum contact with the surface of the road. The way a wheel is oriented on your car is broken down to three major components; camber, caster, and toe in/out.

[Chancer]

[quote user="EuroTrash"]I thought that tracking/wheel alignment corrects the caster angle ie the toe-in toe-out. You make it sound as if it's two different things?[/quote]

 

The adjustment of toe in/toe out is indeed known as tracking or wheel alignment but it has absolutely nothing to do with or any affect on castor (not caster) angle which on 99% of production vehicles is fixed by the suspension geometry and cannot be adjusted.

 

They are indeed two completely different things, castor angle also known as king pin inclination only exists on steered wheels and is what gives self centering and directional stability in conjunction with other variables.

[AnOther]

[quote user="BritinBretagne"][quote user="AnOther"]That's a bit harsh.

If you do something which knocks the tracking out you'll know about it instantly because it will displace the steering wheel from it's normal straight ahead position, something violent enough to do that could even set off the airbag !

[/quote]

Really? Your answer surprises me. Most tracking problems become apparent through tyre wear, the driver being totally ignorant of the situation from his position behind the steering wheel.[/quote]I was talking about a single event which damaged the front suspension or it's geometry, hitting a pothole or a kerb for instance would normally only affect that one side and that would definitely put the steering wheel off centre.

Longer term the tracking can go out of spec. due to wear in the components, principally mounting bushes which become softer and more compliant with age and use and as that progresses it causes the tracing to vary depending on whether the car is accelerating or decelerating/braking. Such deterioration will occur pretty much equally to both sides at the same time however so will not be reflected in the steering wheel alignment, the tyres will still tell the story though. When the wear becomes that advanced there is little you can do with the tracking to prevent continued uneven tyre wear.

To clear up the confusion with terminology this site explains in pictures, castor is normally fixed and a factor of the design, camber is sometimes adjustable, toe in/out always is.

Actually there is a fourth angle called the Ackerman angle as it's but it's a product of the other three so there is no need to go there !

[Chancer]

No need but I"ll go there anyway, Ackermann angle dates back to horse drawn carts and allows the inner steered wheel to take a tighter radius in a curve than the outer one, think of a running track with lanes.

 

A line drawn through the RH front swivel axis passing through the track rod end axis should intersect with the same line from the LH side at exactly the centre point of the rear axle.

[EuroTrash]

Thank you for explaining all that so clearly, Chancer.

No doubt I will forget it again, but for the moment I feel as if I understand :-)

[BritinBretagne]

I had the alignment checked on one of my cars when I had the front tyres replaced by Euromaster in the summer. The equipment used was pretty impressive and showed simulations of what would occur if x, y or z was adjusted. They even checked that the four wheels were in the correct position relative to each other.

[Chancer]

[quote user="EuroTrash"]Thank you for explaining all that so clearly, Chancer. No doubt I will forget it again, but for the moment I feel as if I understand :-)[/quote]

 

It reduces tyre wear especially at full lock during parking manouevres, its not adjustable and even on a fully rose jointed suspension like my race cars we dont concern ourselves with it as it yields no performance or roadholding benefits.

 

However it can really throw things out when modifying a vehicle using the steering arms or complete front suspension from another car with a different track or wheelbase can make the front wheels turn at the wrong angle and cause tremendous tyre scrub, I fitted disk brakes from a scrap HA Viva to my HB Viva by swapping the complete stub axles and the inside wheel turned close to 90° when on lock.

 

Lots of kit cars that use suspension components from donor vehicles have terrible Ackermann tyre scrub problems and also many that are factory built.

 

Regarding kerb impact damage and altering suspension angles, to alter the camber or castor would involve bending a wishbone, control arm or stub axle, all very rigid overengineered components on modern vehicles, you are unlikely to do so without knowing all about it, a ball joint is more likely to break and the wheel collapse, the steering arms are relatively slender struts and can be bent putting the tracking out but it would still be a substantial impact that would try to pull the steering wheel from your grip, 30 minutes of misalignment is enough to create adverse tyre wear but this would would be too small an amount to be wotnessed by the wheel not being centred.

 

Just thought, Ackermann angle is very important on one vehicle steering design, one which I recently had some input in, and that is the Red Bull gravity racers.

[richard51]

From all the technical replies on here I gather that the answer to my second, rather naive, question re uk cars driving on the "wrong" side of the road is that it makes sod all difference to tyre wear.

thank you.

[BritinBretagne]

Did you tyres suffer from driving on the left hand side of the road in England?

[AnOther]

Road camber can affect tyre wear but to a degree so negligible that it's not worth worrying  about.

Swap you wheels around more often if you do.

[Chancer]

Some tyres need a significant steering input to correct the drift from road camber, it can  mask or exaggerate any misalignment of the steering wheel due to tracking knocked out of kilter or could also make you think that the tracking is out when it is correct.

[richard51]

BnB: not really noticed a problem but after a service the Kia dealer suggested that the tracking should be tested. Given that the car has now done 32,000 miles and the tyres are within legal limits I thought it would be better to wait until changing the tyres. ATM tread depth varies between 1,5 mm and 3mm. Will change them soon, before winter sets in Read somewhere that after the tread is down to 3mm then deterioration gets quicker.

Must admit that I don't swap wheels around as suggested but perhaps, as said, I should.

[richard51]

Pot-holes :- ironic but see recent treads

[Chancer]

[quote user="richard51"] Read somewhere that after the tread is down to 3mm then deterioration gets quicker. [/quote]

 

You may have done but it just isn't true, the shorter the tread blocks the stiffer they are, the better they hold the road (except for standing water) and the tyre wear is exponentially less.

 

In race championships where we had to run road tyres you would have them buffed down to 2-3mm before even putting them on the car, you could do several races even endurance races before they wore evenly across the whole tread to the legal limit which could be checked on post race scrutineering.

 

A new unbuffed tyre with 8mm of tread would be worn down to the canvas on the outer treads after one practice session.

 

I have only ever used part worn tyres on my vehicle, 12 years and 211000 kms on 2 sets of tyres (plus the current ones) that had 4 mm of tread each time because the owners were told to change them at that depth, they will have got less than half the mileage out of them that I did.

 

[richard51]

It could it be that this is what I read:

Wet grip in particular gets worse as the tread on your tyres wears. This is more marked as the tyre wears below 3mm of tread and approaches the legal limit. Check your tyre's tread depth more often once it gets down to 3mm and aim to replace tyres before the tread wears below 2mm.6 Feb 2017.

straight google search" tyre wear 3mm".

I must admit that I only want to be safe and not rip around a track at excessive mph. Like you, I also want to get as much value from the tyres as possible but without safety or legal issues. .

[BritinBretagne]

If you are going to drive on wet roads you need tread to displace the standing water. If you only ever run on dry roads you will be fine with shallower tread.

Competition cars use skimmed tyres because less tread means less horizontal movement and better roadholding. As soon as the track becomes wet their tyres become useless. I used to race a National 100 kart. It used slick tyres in the dry, no tread was needed to grip the road, the large patch provided by the treadless tyres was more than enough.

[AnOther]

I always replace tyres at around 3mm, Chancer you are welcome to them gratuit but you'll have to collect [:P]

[Chancer]

[quote user="richard51"]It could it be that this is what I read: Wet grip in particular gets worse as the tread on your tyres wears. This is more marked as the tyre wears below 3mm of tread and approaches the legal limit. [/quote]

 

No argument with that Richard and I did say standing water although wet conditions would have been better, what you posted though was that below 3mm deterioration gets quicker, I took deterioration to mean tyre wear in the light of the previous discussion.

 

3mm is a sensible tread depth to replace the tyres as a compromise between safety and maximum tyre life, the former must take precedence, tread above 3mm does not bring anything to the party.

 

Now money is no longer an issue I will replace mine at 3mm also but will still be happy to use selected part worns.