tyre ware to diagnose alignment "improvements"

[steve b]

Had my alignment done a little while ago (cars only used on track) and I've now come to the point of new tyres. The rears have worn the insides, the fronts the outsides. Does this indicate I should have more front camber, less rear?

 

Its my MX5 / P5 Pure drive suspension, WIM alignment.

 

p.s. Its not a lot of difference in ware, maybe 1mm. I swapped fronts to rears etc to get a bit more out of them.

[Tony]

Difficult call on worn tyres due to their retained wear history?.... by that i mean the actual pattern of wear is not consistent with "now"... The real way to assess the calibration is temperature of the tyres after a few laps on the track.

[steve b]

Difficult call on worn tyres due to their retained wear history?.... by that i mean the actual pattern of wear is not consistent with "now"... The real way to assess the calibration is temperature of the tyres after a few laps on the track.

 

Tyres have only been used with currrent alignment, do hotter areas correlate to more worn areas normally?

[hms]

I have found on track that on the fronts the ouside of the shoulders will wear due to cornering at speed the tyrewalls flex and put the weight onto the outside edge of the tyre. The inside edge of the tyre on the inner of the corner does not suffer as much due to weight being transferred to the outside of the corner.

This can be improved by adding a couple of extra PSI to the tyres, in effect stiffening the tyre and not allowing the sidewall to flex as much.

Alternatively, you can use a more track based tyre which has stiffer sidewalls. The Hornet went from Toyo T1 R's, a road tyre, to Hankook RS2's (iirc) (track/road tyre) with stiffer sidewalls and greatly reduced shoulder wear! Ahopulder wear will be more of a problem at the front due to the steering presenting the tyres at at an angle to the track. (I'm thinking slip angle here is that correct!)

Wear on the rear will be down to camber/toe. More agressive settings will make the rear end feel planted at the expense of tyre wear.

 

Hotter areas of tyres show which part of the tyres are working hardest, and if you measure the temperature on the left, centre and right of the tread pattern across both wheels of an axle, that can tell you something about how the set up is working. (Cannot remember the details of this tho'.)

 

All of this is only my laymans view, so may/will be wrong!

 

h

[MarkO]

I have found on track that on the fronts the ouside of the shoulders will wear due to cornering at speed the tyrewalls flex and put the weight onto the outside edge of the tyre. The inside edge of the tyre on the inner of the corner does not suffer as much due to weight being transferred to the outside of the corner.

This can be improved by adding a couple of extra PSI to the tyres, in effect stiffening the tyre and not allowing the sidewall to flex as much.

Alternatively, you can use a more track based tyre which has stiffer sidewalls. The Hornet went from Toyo T1 R's, a road tyre, to Hankook RS2's (iirc) (track/road tyre) with stiffer sidewalls and greatly reduced shoulder wear! Ahopulder wear will be more of a problem at the front due to the steering presenting the tyres at at an angle to the track. (I'm thinking slip angle here is that correct!)

Wear on the rear will be down to camber/toe. More agressive settings will make the rear end feel planted at the expense of tyre wear.

 

Hotter areas of tyres show which part of the tyres are working hardest, and if you measure the temperature on the left, centre and right of the tread pattern across both wheels of an axle, that can tell you something about how the set up is working. (Cannot remember the details of this tho'.)

 

All of this is only my laymans view, so may/will be wrong!

 

h

as a student you have pritty much hit the nail on the head

[hms]

h

[CIH]

ofcourse something more track focused, with stiffer sidewalls and less compliance, won't be so great for on normal roads ie; following ruts, increased noise etc.

 

I had been tempted to get 888s for my Silvia but I read some reports by owners and don't fancy it so much now TBH.

[Tony]

ofcourse something more track focused, with stiffer sidewalls and less compliance, won't be so great for on normal roads ie; following ruts, increased noise etc.

 

I had been tempted to get 888s for my Silvia but I read some reports by owners and don't fancy it so much now TBH.

 

Their pants in standing water mate

[CIH]

Yeah, but not just that. Noisey enough for passengers to comment, cost, tyre life etc.

[Tony]

Yeah, but not just that. Noisey enough for passengers to comment, cost, tyre life etc.

 

Maybe that's why their only available to race orientated company's now?

[hms]

More info on tyre temps v alignment.

I'll try and explain without pictures, as I don't do pictures!

 

Tyre temps taken in 3 places, outer and inner edges of the tread, the third being in the centre of the tread. Temps must be taken immediately the car has stopped.

 

The middle reading should be the average of the outside readings.

Lower tyre pressure if the centre reading is too high. Raise pressure if centre temp is too low.

 

If one edge of the tyre is higher than the rest of the tyre then you have too much camber at that edge.

 

If one end of the car is noticably hotter that the other, then appropriate sway (ARB) adjustments need to be made. (Can't get my head around this, how the ARB's on one axle affect the tyre temp on the other axle!)

 

My understanding would be that temperature equates to tyre wear, so, providing tyre temps are correct, on the track you can see by temperature how the tyre will wear, and inform you of how the alignment is working, removing the driver from trying to explain how the car is handling when they may not have the neccessary vocabulary/experience to do so. This allows Tony to tune the alignment without having to wear a set of tyres out to get the wear pattern showing or trying to interpret what the driver says about the handling!

 

But again, I may be totaly off the mark!

 

h