4 replies to this topic

[Propshaft]

Just set up to do the tracking on my 92 mini is it best to measure off the wheel or the tyre and is the 1 to 3 mm tracking at the rear each side Thanks

[Midas Mk1]

Always wheel rim, you will get deflection from the tyre. 

[absx2]

On the rear you need to find and mark the dead center of the car and then go off each side from the center or you can end up with all the toe in on one side.

I have more luck with a couple of wood battens at identical lengths with the rim diameter marked on the ends then measure off that. That`s how it was done back in the day .

Even the local laser alignment guys made a mess of my mk3 but doing it with wood fixed my wayward road holding.

I try for 1.6mm or 2mm each side but some go parallel but it`s dangerous if it toes out due to wear or misalignment.  

[68+86auto]

Simply answering one or the other is incorrect.

 

The rim will not be straight if you spin it and the tyre will be out too. With basic equipment you need to measure at a certain point and then roll the car forward and measure at the same point. The manual specifies a certain diameter which is on the tyre. With professional equipment runout compensation is performed.

 

The most accurate way to do this without professional equipment is to go back to the methods of early professional equipment. Jack up the wheel and place a tyre scribe (spring loaded pointer) on the ground against the tyre tread (or for less accuracy use chalk). When you spin the wheel it scribes a line which is true to the rotation of the wheel. you can then use a bar with two pointers to measure the distance at the front and back of the tyre at the same height (or use a tape measure).

[Steam]

Try a string line around all 4 wheels to show both front and rear tracking. Just make sure to get steering centralised.