Wheel/Tyre size impact on alignment settings

[New Duke]

Having had my suspension replaced with the new PZ kit it's time to get the wheels aligned. The steering occasionally 'wanders' on the road and track and it's not been aligned since 2016, and that was only to Mazda's vague specs. So it feels badly needed. I intend to get the garage to set it up focused for track use once I've figured out ballpark settings.

I was intending to have it set up with my track 18inch wheels and 225/40/18 tyres which I assume makes the ride height a bit lower than my road 19inch wheels on 225/40/19. I don't really have the space or even surface to accurately measure the difference in ride heights at home. But from reading ride height seems to form the basis of all adjustments.

Does anyone have thoughts on whether after setting it up for track on smaller wheels the handling would be (significantly) impacted by then using larger (but lighter) 19s on the road?

I plan on driving the NC500 and Alto de Velefique in Spain this year so want to have it both ways in what essentially is now my track car.

[13Black]

The ride height which I think you're referring to with alignment is how compressed the springs are depending on how weighted the car is - distance between top of wheel arch and wheel centre.

You can fit monster truck wheels/tyres to alter the ride height but this alignment measurement won't change, so I don't think you should be concerned.

[PeteH]

Wheels and tyres have no affect on the geometry settings. The camber, caster, and toe settings, and the ride height (measured from the wheel centre to the wheel arch) are all totally unaffected by whatever wheels and tyres you fit.

Fun fact. F1 cars have their wheel alignment done with no wheels fitted.......

[New Duke]

Just to confirm those answers

alignment table.jpg

"Vehicle height: From the end of the fender to the centre of the wheel"

You could check the alignments with the wheels removed, as long as the weight of the car is on the hubs.

[New Duke]

Excellent thanks guys. Yep I'd misunderstood ride height. That's good news to read. Will even save me putting the track wheels on when I get it done.

[13Black]

Similar to the above, when I fit suspension and have to tighten bushes up in their 'loaded' position: I don't have the wheels on, I just plonk a jack under the correct place on whatever corner it is and jack it up, then measure the distance from the bearing centre to the top of the arch to make sure they're not strained once it's back on the ground.

[New Duke]

Similar to the above, when I fit suspension and have to tighten bushes up in their 'loaded' position: I don't have the wheels on, I just plonk a jack under the correct place on whatever corner it is and jack it up, then measure the distance from the bearing centre to the top of the arch to make sure they're not strained once it's back on the ground.

Just one of the many reasons why I'm selfishly sad you're stopping mate. Happy for you obvs but... y'know.

[SeeJay]

Similar to the above, when I fit suspension and have to tighten bushes up in their 'loaded' position: I don't have the wheels on, I just plonk a jack under the correct place on whatever corner it is and jack it up, then measure the distance from the bearing centre to the top of the arch to make sure they're not strained once it's back on the ground.

Having watched Nick fit my coilovers over a year ago,and my RacingBeat ARB's even longer ago,I can attest that he knows all about suspension 'preload'..

Just one of the many reasons why I'm selfishly sad you're stopping mate...

.. but what's all this about 'stopping'

What am I missing here

[13Black]

No longer working on cars and doing software development instead, is me Nick 13Black, we have met before I'm sure of it

[SeeJay]

What about the vintage stuff

[13Black]

Daddyo can carry on making an absolute minimal-effort bodge of everything at his own leisure without my constant 'moaning' that standards aren't good enough. I can't be having my name on the things he puts out any more - it's only a matter of time before an enormous bill for a failed part comes to bite or someone else gets hurt.

[warpc0il]

uch: