245 vs. 235 (18") - Talk to me Goose!

[Gsxr150]

So, I've narrowed down my tire brand/model choice, but now I'm wondering about going with 245/40R-18, vs factory size 235. I've read all the forums I can, but there's no clear cut review from someone actually going with 245 vs 235.

Anyone running a 245 tire on their Aero 18's? If so, would you do it again?

 

[TomB985]

Just curious what you were looking to improve with a wider tire? Is it a performance thing or something else?

 

[XLR82XS]

I plan on replacing tires with 245 when the OE rubber gives up the ghost. More curb protection and increased handling. (19")
Continental PureContact LS.

 

[cypho]

I have 245/45R18 winter tires on my model 3. Love them. When it comes time to replace my summer/all season tires I will go that size too.

I hit a curb for the first time a few weeks ago, (and was wearing the 245s) it made an awful sound and I assumed that my rims were going to be all messed up. But the extra with and height saved the day. I still have flawless rims.

/45 is closer to OEM than /40. 1.5% circumference difference vs 2.3%. Plus the extra height will give you more protection and a softer ride. And imo looks better too.

 

[Marius A]

I have 245/45R18 winter tires on my model 3. Love them. When it comes time to replace my summer/all season tires I will go that size too.

I hit a curb for the first time a few weeks ago, (and was wearing the 245s) it made an awful sound and I assumed that my rims were going to be all messed up. But the extra with and height saved the day. I still have flawless rims.

/45 is closer to OEM than /40. 1.5% circumference difference vs 2.3%. Plus the extra height will give you more protection and a softer ride. And imo looks better too.

Track pack (selectable through TPMS reset) is 245/35/20
According to Tesla SC in Norway when you select a different rim size in that reset window the speedometer will take that into account. Still haven't tested it, though.

Edit: I went with 235/45/18 on my Performance, don't regret not picking 245.
I would go for whatever gives you the cheapest, highest performing tire.

 

[cypho]

Track pack (selectable through TPMS reset) is 245/35/20
According to Tesla SC in Norway when you select a different rim size in that reset window the speedometer will take that into account. Still haven't tested it, though.
View attachment 624470

Edit: I went with 235/45/18 on my Performance, don't regret not picking 245.
I would go for whatever gives you the cheapest, highest performing tire.

I don't think you understood my point about /45 vs /40. 245/45R18 is closer to OEM 18's than 245/40R18. If you tell the car that you are on 245/35R20 it makes the spedo error from 245/40R18 worse than leaving it set to normal 18's.

But on the subject of speedometer errors, I actually think the speedometer offset from a slight step up in diameter is a good thing. From what i have seen watching the car's canbus data, It makes the speedometer more accurate.

The car's display always rounds up. If the car thinks it is going 59.1 (according it's own canbus data), it will display 60 on the screen. And if I set cruise to 60, according to the canbus, the car seems to actually aim for 59.1. And that is not even taking into account that once the tires begin to wear down they will become smaller and the car will be going even slower than that when you set it to 60.

So with the +0.9 mph offset (at 60mph) from using slightly larger 245/45r18 tires, when you set cruise to 60, you will actually be going 60.0.

 

[Marius A]

I don't think you understood my point about /45 vs /40. 245/45R18 is closer to OEM 18's than 245/40R18. If you tell the car that you are on 245/35R20 it makes the spedo error from 245/40R18 worse than leaving it set to normal 18's.

But on the subject of speedometer errors, I actually think the speedometer offset from a slight step up in diameter is a good thing. From what i have seen watching the car's canbus data, It makes the speedometer more accurate.

The car's display always rounds up. If the car thinks it is going 59.1 (according it's own canbus data), it will display 60 on the screen. And if I set cruise to 60, according to the canbus, the car seems to actually aim for 59.1. And that is not even taking into account that once the tires begin to wear down they will become smaller and the car will be going even slower than that when you set it to 60.

So with the +0.9 mph offset (at 60mph) from using slightly larger 245/45r18 tires, when you set cruise to 60, you will actually be going 60.0.

Yes, but if you set it to 245/35R20 then the 245/45/18 is only -0.4%, so even more accurate.
But yes, it rounds up, which can be nice when you drive past speed cameras on a decline or in a bend. Depending on how strict the cameras are in your country.
The biggest pain about having a very correct speedometer is that nobody else has it

 

[Gsxr150]

Just curious what you were looking to improve with a wider tire? Is it a performance thing or something else?

That's why I'm asking the question! I've seen a few people chatting about it and I'm curious why a guy would purchase 245 vs 235.

 

[Gsxr150]

I don't think you understood my point about /45 vs /40. 245/45R18 is closer to OEM 18's than 245/40R18. If you tell the car that you are on 245/35R20 it makes the spedo error from 245/40R18 worse than leaving it set to normal 18's.

But on the subject of speedometer errors, I actually think the speedometer offset from a slight step up in diameter is a good thing. From what i have seen watching the car's canbus data, It makes the speedometer more accurate.

The car's display always rounds up. If the car thinks it is going 59.1 (according it's own canbus data), it will display 60 on the screen. And if I set cruise to 60, according to the canbus, the car seems to actually aim for 59.1. And that is not even taking into account that once the tires begin to wear down they will become smaller and the car will be going even slower than that when you set it to 60.

So with the +0.9 mph offset (at 60mph) from using slightly larger 245/45r18 tires, when you set cruise to 60, you will actually be going 60.0.

Gotcha. So if a softer ride is the goal, then perhaps change from OEM size. But it sounds like no performance gains by going 245.

 

[Marius A]

Gotcha. So if a softer ride is the goal, then perhaps change from OEM size. But it sounds like no performance gains by going 245.

It depends
Wider usually performs better on dry, hard surfaces (ie: not gravel), lower profile has less roll.
It's going to be heavier and might be noisier, again YMMV, and 235 vs 245 isn't a big deal.

 

[Sam1]

That's why I'm asking the question! I've seen a few people chatting about it and I'm curious why a guy would purchase 245 vs 235.

Depends on if you are losing traction with the 235's if you will see performance gains with the 245's. If you're not having traction problems with 235's, there's no reason to get wider tires.