Replacing 19" Gemini wheels on MY RWD?

[Midnight Man]

This thread (Wider tyres for Model Y Gemini) has prompted me to wonder whether replacing the standard 19" Gemini wheels on the MY RWD with 18" wheels and an appropriate tyre is a possibility?

I didn't want to hijack that thread, so thought a new thread more appropriate for this discussion.

I'm nowhere near knowledgable in this sort of thing, but looking at it purely logically, I figure you could get a higher profile tyre which should lead to a more comfortable ride. You alos gain the advantage of less worry over kerb rash, and potholes.

At 18", the cost per tyre comes down significantly (and would fairly quickly pay for a set of wheels perhaps), and you could perhaps aim for a slightly shorter circumference, which would "pad" your speedometer readings to include a more traditional 2-3km of "overstated" speed - something we are all used to in our ICE vehicles, but I understand is not the case in a Tesla?

Happy to be told I'm wrong on all of the above, but I'd really appreciate thoughts from the wise community!

 

[Onshore]

Tsportline has a very good summary here

But yes, you can fit 18” wheels as long as they clear the brakes.

They recommend 245/50-18 rubber

The Tesla Model Y Wheel Guide

Find Tesla Model Y Wheel and Tire Specs here! Looking for Tesla Wheels? See all of T Sportline's Tesla Wheel offerings for the Tesla Model Y from turbine style, arachnid style, and forged wheels! Shop Tesla Model Y Aftermarket Wheels now!

tsportline.com

 

[Quickst]

I understand is not the case in a Tesla

All vehicles are supposed to overread to some degree. It display a speed that is faster than actual

current ADR:
The speed shall not indicate less than the true speed of the vehicle.
The relationship between displayed speed (V1) and the true speed (V2) is:

0 <= (V1-V2) <= (V2+4km/h) x10%

Basically this means that if true speed is 110kmh then displayed speed (= speedo reading) must not be less than 110km/h OR not more than 11.4km/h

I dont know what Teslas are reading. But it would be silly to read exactly the same as true speed as lots of other factors can affect display speed such as tyre pressure, tyre wear. .

But interested to hear of what you find @Midnight Man !.
Am I right in saying that range increases a bit if a larger profile tyre is used?.

 

[Blue heaven]

All vehicles are supposed to overread to some degree. It display a speed that is faster than actual

current ADR:
The speed shall not indicate less than the true speed of the vehicle.
The relationship between displayed speed (V1) and the true speed (V2) is:

0 <= (V1-V2) <= (V2+4km/h) x10%

Basically this means that if true speed is 110kmh then displayed speed (= speedo reading) must not be less than 110km/h OR not more than 11.4km/h

I dont know what Teslas are reading. But it would be silly to read exactly the same as true speed as lots of other factors can affect display speed such as tyre pressure, tyre wear. .

But interested to hear of what you find @Midnight Man !.
Am I right in saying that range increases a bit if a larger profile tyre is used?.

I’m not sure how much efficiency will improve dropping from 19 down to 18 but dropping from 21 to 19 improves efficiency by approximately 11% on a Performance model Y.

 

[Midnight Man]

Well, it sounds to me like this is possible to achieve - thank you to those who have posted.

I haven't got my car yet, so I figure I will leave well enough alone and ride on the stock wheels and tyres - when it's time to start looking for a replacement set of tyres, I will have a chat to a local tyre place (likely Beaurepairs etc.) and see what they can offer.

It'll be a while away, but I will do my best to come back to this thread with any findings on range

 

[nishank93]

speedometer readings to include a more traditional 2-3km of "overstated" speed - something we are all used to in our ICE vehicles, but I understand is not the case in a Tesla?

Relative to my phone's GPS speed, my ICE car overstates by about 2-5% (depends how old the tyres are).
My ~90km old Tesla MYLR overstates by about 2%.

Both cars have GPS and fully digital dashes, so in theory could simply report GPS speed, but I'm not sure any car actually does this. Most (all?) modern cars report speed by measuring tyre rotations using a hall-effect sensor mounted to the driveshaft, and multiplying by stock OEM tyre circumference. This is generally calibrated to be on the safer side, to allow for variations in tyre size/pressure/age/etc.

 

[AUSEd]

The key consideration is when you are dropping down tyre size is
1. The overall diameter of the tyre must be the same or within tolerance. A good tyre shop will help you.
2. The load index of the 18” tyre must be the same or greater than 19” tyre.
3. Tyre width and brake considerations.

To be perfectly honest just use the 19” wheels. If you want to save on 18” wheel you need to buy 4 18 rims so it take time to recoup.

If you shop around you will find Hankook replacement elsewhere. Don’t buy tyres at Telsa.

Eg the 3P tyres at Telsa are around $750. MyCar has them for $675. Tempe Tyres has them for $450. Someone I knows got MyCar to price match them to $450 and they did.

 

[AUSEd]

I did some more looking around. A standard 19" is 255/45/19

Tempe Tyres price is $410

MyCar price is $665

So you ring up MyCar and ask them for a price match and they will honour it.

Nice and simple

 

[Quickst]

Tempe Tyres price is $410

Bugger, price went up. On the weekend when Iooked they were $350.
I suppose price changes from time to time

1. The overall diameter of the tyre must be the same or within tolerance

I dont think there is a "tolerance", Just need to be aware that tyre circumference affects speedo, odo, and torque
Close as possible to OEM is best
A reference guide to wheel and tire sizes for your car helps with the calculations