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Sorry, that's really poorly explained.

A 20" Tesla rim and tyre is 235/35 R20. 235 is the width of the tread, 35 is the height of the sidewall as a percentage of the width of the tread, and the 20 is the diameter of the rim the tyre fits to. The above tyre has 81mm of sidewall and a circumference of 2111mm. If you change to 18" rims, you'll need to find a tyre that keeps the circumference as close to 2111mm as possible, otherwise your speedo will be dramatically inaccurate. To roughly match that same circumference on an 18" rim, you'll need a 235/45R18 tyre. This has a sidewall height of 107mm and a circumference of 2101mm, which is only 0.8% difference in circumference, but a decent 31% increase in sidewall height, and therefore better rim protection against potholes (there's more tyre to get through).

Hubs have no say in the wheel size or the tyre size. They're the bit you bolt the wheel to the car at.

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The volume of air in the tyre, which provide provide a flexible cushion that absorbs shock as the tire rolls over rough features on the surface, is greater in the higher profile tyre. The more voluminous flexible cushion of air provides a better ride and greater protection to the inflexible wheel on which it sits.
 
Some of this discussion misses the point of large diameter wheels with low profile tyres, which is the improvement in response and handling. This is why they are fitted to the performance model.
Turn-in is better, as is acceleration because there is less “squish” in the tyres.
As I said up-thread, all of my previous cars (in the last 15 years) have had low profile tyres, and I have never damaged a rim.
 
This is why they are fitted to the performance model.
No, that's marketing.

Turn-in is better,

Yes, initial turn in is more direct due to no flex in the sidewall.
as is acceleration because there is less “squish” in the tyres.
No, look at the fastest accelerating cars in the world, top fuel dragsters, the biggest baggiest tyres.

Also F1 moving to 18inch rims from 13 inch, expected to cost 2 secs per lap.


"All things being equal the bigger rims, low-profile rubber is always going to be a worse tyre than the sort of tyres that we have on our racing car today,” - James Allison, Mercedes F1 Technical Director
 
No, that's marketing.



Yes, initial turn in is more direct due to no flex in the sidewall.

No, look at the fastest accelerating cars in the world, top fuel dragsters, the biggest baggiest tyres.

Also F1 moving to 18inch rims from 13 inch, expected to cost 2 secs per lap.


"All things being equal the bigger rims, low-profile rubber is always going to be a worse tyre than the sort of tyres that we have on our racing car today,” - James Allison, Mercedes F1 Technical Director
Road tyres on road cars are not the same as baggy slicks on drag cars, nor are they the same as racing slicks on racing cars.
I’ve been racing a car for over 10 years now, won a few and lost a few :) so I do know the difference.
Low profile tyres give a road car better handling and acceleration, especially in an AWD car like the M3P
 

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My Audi A3 (225 x R45 Tyres) I always set to 40psi and this is perfect. Most people under pressure their tyres. I think on my mates Tesla RWD it says 42 psi on the label inside the door. I guess I’ll find out if and when I get mine. I am not sure if it varies on the model type.
 
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The 18s have the same rolling diameter as the 19s - higher profile tyres are used - so the ground clearance should be the same.

(My SR+ with 18s had a single 19" loaner wheel on it for a few days at one point!)
Thanks for clarifying that cafz! Hopefully anyone else wondering about wheel size vs ground clearance on the Model 3 can benefit from your answer. ;)
 
Thanks to the *sugar* roads in Australia…. I would prefer the 18 over anything larger, as the larger tyres are ‘thinner’. My friends who own the P models tells me about their tyre problems on a daily basis
Hi IcedCoffee, I ended up calling an SA to ask them about the benefits of moving down to the 18" from the 19" (which will not result in a refund for difference in cost, in case anyone was wondering).

I did voice my concern about the ample anecdotal feedback regarding the 19" being more susceptible to pothole damage, but he did bring up a valid point, it really depends on your driving style and how fast you're going when you hit a given pothole. He also mentioned that he personally has a Model 3 LR that has 19" wheels and he hasn't had any issues with potholes so far.

He also mentioned that, ideally to capitalise on $$$ I should probably look at picking up 18" wheels after-market if I change my mind about the 19" wheels, selling the latter for a little bit of $.

For anyone still wanting to switch from 19" to 18" though, the SA mentioned that it would not impact/affect your place in the queue, nor will it impact the purchase price. :)
 
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Hi IcedCoffee, I ended up calling an SA to ask them about the benefits of moving down to the 18" from the 19" (which will not result in a refund for difference in cost, in case anyone was wondering).

I did voice my concern about the ample anecdotal feedback regarding the 19" being more susceptible to pothole damage, but he did bring up a valid point, it really depends on your driving style and how fast you're going when you hit a given pothole. He also mentioned that he personally has a Model 3 LR that has 19" wheels and he hasn't had any issues with potholes so far.

He also mentioned that, ideally to capitalise on $$$ I should probably look at picking up 18" wheels after-market if I change my mind about the 19" wheels, selling the latter for a little bit of $.

For anyone still wanting to switch from 19" to 18" though, the SA mentioned that it would not impact/affect your place in the queue, nor will it impact the purchase price. :)
Yea, fair enough. That’s also one of my speculations that my friends with P models just like to drive faster than they should, which might be attributing to their rim damages…(and speeding/red light tickets in the mail😂)