Spare wheel, M3 to MY question

[alset tone]

I will soon (hopefully May) trade my Model 3 in for a Model Y.

I have an 18" steel spare wheel for my M3, with a tyre size of 135/80 18.
I understand the tyres on the MY 20" induction wheels are 255/40 20.

I am assuming the hubs/stud PCD, are the same on both cars.

I'm having difficulty (I'm old) working out the rolling diameter of each wheel, as I'm not sure what/how the aspect ratio on the tyres change things. Could some knowledgable person tell me if I could use my 18" M3 spare on my 20" wheeled MY safely or would the rolling diameters be too far apart? Could it do any damage (differential etc) to the car if the rolling diameters are too far apart?

 

[Toblerone]

Not a chance.

I mean they shown it fitted to a Y with 20s. Not better than waiting for a flatbed?

 

[MrT3]

I mean they shown it fitted to a Y with 20s. Not better than waiting for a flatbed?

???

Not a chance was in reply to your “Anyone know if it will fit in the frunk or under the boot floor storage?” question.

 

[Wattsisname]

Tesla Model Y Road Hero Spare Wheel Kits | Carnoisseur

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it's 18" but within limits to suit the 19" wheels. I'll probably sell my M3 one and get one of these

There is this as well but i'd want to know the tyre size first

18" TESLA MODEL Y | Space Saver Wheel | The Wheel Shop

Cheap Spare Wheels & Space Saver Wheels - Thewheelshop.co.uk 18" Space saver spare wheel + cover bag compatible with Tesla Model Y (2020-present day)

www.thewheelshop.co.uk

I like the sound of the Road Hero Wheel; the suppler's ad states that it come with a Tesla specific jack ( ).
Jacking is the other component of the dreaded puncture situation.

 

[Bernard_S]

???

Not a chance was in reply to your “Anyone know if it will fit in the frunk or under the boot floor storage?” question.

Ooooops ! Forgot to use quote.

 

[Wattsisname]

I like the sound of the Road Hero Wheel; the suppler's ad states that it come with a Tesla specific jack ( ).
Jacking is the other component of the dreaded puncture situation.

Any thoughts on jacking up ( I don't mean the price) the Model Y LR?