# stock 18" aero wheels - 255/40-18 ?



## Ole1

has anyone put 255/40-18 (what tire ?) on their stock 18" aero wheels ?
.... it would be nice to know 100% certin before i buy .... but hopefully, tire shop will be ok with checking 255/40-18 and 245/45-18 .... 
... planning on michelin pilot sport 4S ....


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## garsh

Ole1 said:


> has anyone put 255/40-18 (what tire ?) on their stock 18" aero wheels ?


I'm planning to get 245/45R18 winter tires on aftermarket 18" rims.
I'll try to remember to followup here if there are any issues, but I don't expect there to be.


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## Johnston

Ole1 said:


> has anyone put 255/40-18 (what tire ?) on their stock 18" aero wheels ?
> .... it would be nice to know 100% certin before i buy .... but hopefully, tire shop will be ok with checking 255/40-18 and 245/45-18 ....
> ... planning on michelin pilot sport 4S ....


Have you tried entering your M≡'s information (make, model, wheel size) into Tire Rack's search to see what's compatible? I remember entering info for my CX-5 and I believe the most I could go is 10mm wider. 255 from 235 might be too much.


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## rlb4

Both sizes are similarly different from the stock size of 235/45 18. 255/40 is a little less diameter with shorter sidewall, increased wheel gap, decreased ride height, and greater tire lip. The 245/45 is a little greater diameter and has a bigger sidewall, decreased wheel gap, increased ride height, and a slightly greater tire lip(less that the 255/40). Both will increase the offset due to being wider. I am going to go with the 245/45 because I think it has less of the negatives(decreased range, increased wheel gap) while keeping most of the positives(better traction, decreased wheel gap, increased offset).


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## Ole1

Michelin Pilot sport 4s, 255/40-18 fit just fine ( insert smiley icons )
... time to take her back to the track .....


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## Agon

That seems to make a bit of difference visually actually. Is it your real life experience as well?

Looks great!


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## Feathermerchant

Check the specs on Tire Rack. The 255 may not be much wider (tread width) than the 245.
235/45-18 7.6"
245/40-18 8.4"
255/40-18 8.7"
255/35-18 8.8"

Ole1 - Are those the Tesla 18" wheels?


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## Ole1

Stock Tesla 18" Aero Wheels .... And I agree, they do look pretty cool to me

... 255 Michelin 4S "look" A WHOLE LOT wider than stock Aero Tires (Michelin MXM ? )
- putting on my teenager mindset ... imho - they look totally badA$$ ....


And I forgot to mention, the 255s now stick out past the rims a little bit ---- maybe less chance of curbing
(we have already curbed the first set of wheels with stock tires more than once)

Curbed wheels will be used for snow's after we retire in a couple years and move to a colder climate ....


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## Agon

That sounds really promising. I hope 245/45 with its larger diameter to fill the wheel arch gaps a little bit more - but still some of the feel of a wider wheel like yours - will be the sweet spot for me.


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## Jim H

Ole1 said:


> Stock Tesla 18" Aero Wheels .... And I agree, they do look pretty cool to me
> 
> ... 255 Michelin 4S "look" A WHOLE LOT wider than stock Aero Tires (Michelin MXM ? )
> - putting on my teenager mindset ... imho - they look totally badA$$ ....
> 
> And I forgot to mention, the 255s now stick out past the rims a little bit ---- maybe less chance of curbing
> (we have already curbed the first set of wheels with stock tires more than once)
> 
> Curbed wheels will be used for snow's after we retire in a couple years and move to a colder climate ....


Good look, something I am considering, especially if I get "track mode" upgrade. 
Any rubbing on the inside front? Not a lot of clearance on the stock tire.


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## Ole1

have not seen or heard any rubbing ... but only doing city driving so far .... I should have her back on the track with these tires on Dec 14 .... 

Tire shop where I got them, the manager also owns a model 3 RWD, which he put on staggered Pilot 4S, 235 front, 265 rear
.... he also told me that he has put several sets of 255/40-18s on Model 3s ....


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## Jim H

Ole1 said:


> have not seen or heard any rubbing ... but only doing city driving so far .... I should have her back on the track with these tires on Dec 14 ....
> 
> Tire shop where I got them, the manager also owns a model 3 RWD, which he put on staggered Pilot 4S, 235 front, 265 rear
> .... he also told me that he has put several sets of 255/40-18s on Model 3s ....


Good to hear. You should see a big improvement at your upcoming track event over the MXM's.
Not sold on the staggered approach. Car has some push tendency, and with the wider rears, that will make that worse. I think the square setup you have will perform quite well. Also interested in tire pressure's you go with for the track.


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## Milo

I have an opportunity to buy some 255/40 R18 winter tires off someone's BMW M4. They have OEM BMW rims, which I suppose I could use, but it would certainly look a bit odd. I have a spare set of Model 3 wheels and tires I was planning on using.


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## MountainPass

Jim H said:


> Good to hear. You should see a big improvement at your upcoming track event over the MXM's.
> Not sold on the staggered approach. Car has some push tendency, and with the wider rears, that will make that worse. I think the square setup you have will perform quite well. Also interested in tire pressure's you go with for the track.


Square setup for life.


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## Feathermerchant

You mean tire life because you can rotate a square setup?


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## MountainPass

Feathermerchant said:


> You mean tire life because you can rotate a square setup?


*Square setup for the rest of my life


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## RUN TM3

Nice, I was thinking about 255s down the line. How negatively do the 255s affect mileage?


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## Jim H

MountainPass said:


> Square setup for life.


Sasha;

Now with track mode, and the ability to induce oversteer, is a staggered setup now more workable?


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## MountainPass

Jim H said:


> Sasha;
> 
> Now with track mode, and the ability to induce oversteer, is a staggered setup now more workable?


We aren't in the business of making people feel bad about their wheel choices, but square will always be faster, especially on the Model 3. We are talking about a well balanced car that can run 275s all around, it's not a Porsche with all its weight in the rear. There's no reason to run smaller tires than what you can fit in the front.


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## Feathermerchant

Square also always has the advantage of rotation so you can make them last a little longer.


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## MountainPass

Feathermerchant said:


> Square also always has the advantage of rotation so you can make them last a little longer.


I have staggered, directional tires on my Mr2 (sometimes it's ok!) It's a nightmare because I can't rotate them at all, not even side to side!


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## PNWmisty

MountainPass said:


> I have staggered, directional tires on my Mr2 (sometimes it's ok!) It's a nightmare because I can't rotate them at all, not even side to side!


Oh well, nothing another $1000 for a new set of tires can't remedy! I guess that's not too environmental but..whatcha gonna do?


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## lemketron

Ole1 said:


> Michelin Pilot sport 4s, 255/40-18 fit just fine ( insert smiley icons )
> ... time to take her back to the track .....


I'm trying to decide between PS4S 245/45 and 255/40.

Have you noticed any impact on efficiency with the 255/40? 
Did you happen to track overall efficiency before and after the tire change?

I'm at 13K miles so far with a lifetime efficiency of ~260 Wh/mile on the 18" OEM tires on my LR RWD with the Aero covers always installed.

On a related note, I found a review of the PS4S on the Michelin site that suggests that they aren't great on the track. Curious if you've found otherwise...


> PS4S: Great on street, DO NOT Track 7 months ago
> Put a set of these on my CTS V, and loved them on the street. Quiet, much better grip in cold and wet conditions. The flip side of this is I took the car to the track, fun day one, left front tire separated day two. Tires had around 2,500 miles on them, and were done. Michlin was good to credit me for most of the cost for a new set, and told me not to track these tires. So unfortunately, they performed very well on day one on track, took my lap time down from the Super Sports, just did not last long. Did pull 1.27g's in a corner, but only good one day on track. my recommendation is for street use only, better than SS.


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## Ole1

never tracked efficiency ... but they definately would have reduced efficiency compared to the stock 18s .... 
with respect to the track, I only ran a short track ... kind of like an autocross ... 
For more info on track ... see posts by "JAD" .... it seems like for serious track junkies, you will need dedicated track tires which will survive the heat generated by our heavy cars ..... but for weekend canyon carvers and autocrossers, the PS4S should be fine ?
.... see JADs post here: https://forums.tesla.com/forum/forums/big-track-review-track-mode


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## lemketron

Ole1 said:


> never tracked efficiency ... but they definately would have reduced efficiency compared to the stock 18s ....


Really? You never noticed any Wh/mile numbers, either on the original tires, or after replacing them? If you've never reset either of the trip odometers (where you surely would have noticed the numbers) then they should have a combined number... It would be interesting to reset one of them at this point and see where it settles compared to what the other one is reading...


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## Ole1

Sorry, I have never checked wh/mile ... and ps4s were only on our stealth p3 long enough to run out to the track, run track, and back home ....


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## JJJ784

i'm still tempted to go 265/40/18 on the stock aero wheels with 3mm spacers in the front. maybe 5mm. this will keep the overall tire diameter the same as stock.


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## Aspera

I have two questions.

1) Since the Model Y will come stock with 255’s, will it use different suspension parts that could be retrofitted to a Model 3?

2) Will a larger or smaller diameter tire improve acceleration? The low end torque and excellent traction control of the Model 3 make this one more tricky than a normal car.


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## PNWmisty

Aspera said:


> I have two questions.
> 
> 1) Since the Model Y will come stock with 255's, will it use different suspension parts that could be retrofitted to a Model 3?


No one knows yet but it would be surprising (to me) if they were interchangeable in a bolt-on fashion due to the unavoidable differences in the weight capacity ratings (among other things).



> 2) Will a larger or smaller diameter tire improve acceleration? The low end torque and excellent traction control of the Model 3 make this one more tricky than a normal car.


A smaller diameter tire improves acceleration even more than the same decrease in rim diameter (assuming the tire diameter remains unchanged). The primary reason for this is torque multiplication due to the smaller diameter of the drive wheels. This effect is considerable and it is on top of the improvement gained through the effect of less rotational inertia of the smaller diameter tire.

Many a modder has been shocked by how much slower their vehicle was when they _increased_ the tire diameter without also _reducing_ the gear ratios to compensate.


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## Jim H

Aspera said:


> I have two questions.
> 
> 1) Since the Model Y will come stock with 255's, will it use different suspension parts that could be retrofitted to a Model 3?
> 
> You can fit 255's on the stock 18" Aero's, which was reported in this discussion. I suspect the Model Y would come with similar if not the same suspension parts as the Model 3, to keep built cost down.
> 
> 2) Will a larger or smaller diameter tire improve acceleration? The low end torque and excellent traction control of the Model 3 make this one more tricky than a normal car.


Smaller diameter tire will improve acceleration, as long as the tire choice can handle the torque produced under acceleration (Wider, better traction tire). Look at it as installing higher gears to improve acceleration in an ICE car. 
What your give up is top end speed, range, and maybe ride quality. Lighter wheel will also improve acceleration.


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## Feathermerchant

A 245/45 18 will fit on to a Model 3 with no mods. I know because that's what I have now.
Since an electric car has a completely different torque curve from an ICE car, increasing the tire diameter may be the right thing to do for 1/4 mile time.
I think the Model 3 performance has a lower 0-60 time than a Hellcat Widebody but will lose out in the 1/4 mile.
3.2 vs 3..4 sec 0-60 and 11.7 vs 10.9 sec 1/4 mile.


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## Jim H

Feathermerchant said:


> A 245/45 18 will fit on to a Model 3 with no mods. I know because that's what I have now.
> Since an electric car has a completely different torque curve from an ICE car, increasing the tire diameter may be the right thing to do for 1/4 mile time.
> I think the Model 3 performance has a lower 0-60 time than a Hellcat Widebody but will lose out in the 1/4 mile.
> 3.2 vs 3..4 sec 0-60 and 11.7 vs 10.9 sec 1/4 mile.


The tire that is being used now in SCCA's Pro Solo competing M3P, on 19x8.5 wheels are 265's, so no problem with a 255. Also an earlier post in this tread has 255's mounted on stock 18"s with no problem. 
As far as diameter of tire for 1/4 mile, a shorter tire should give a faster et, a taller tire should give a faster mph. This has been shown on the Tesla Racing You Tube channel with the white Model S that has the current fastest 1/4 mile times. He tested shorter and taller tires and that was the results on a model S. 
As far as beating a Hellcat, it takes a fair amount of skill to launch a Hellcat. A good driver in Hellcat with drag radials will be tough to beat.


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## Feathermerchant

Have you got a link to those tire dia tests? I'm sure there is an optimum tire diameter for lowest ET. Maybe two diameters assuming traction is not a problem.


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## Jim H

Feathermerchant said:


> Have you got a link to those tire dia tests? I'm sure there is an optimum tire diameter for lowest ET. Maybe two diameters assuming traction is not a problem.


I'm not sure about an optimun tire diameter for lowest et, but this test shows what different tires will do for et and trap speeds. Model S could not use the 18's, but compared the difference between the 21's and 19's. When trying to choose what we want to achieve with performance, sometimes there are best street choices, and best track choices. This is why we sometimes need more than one set of rims/tires.


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## Feathermerchant

He swapped tire and wheel sizes making it much more difficult to compare. I was referring to overall tire diameter. Of course you should always use the smallest dia wheels as they are lighter. Even though the tire for the smaller diameter wheel has more rubber, rubber is less dense than aluminum. So the overall combo should be lighter. Besides look at a dragster or funnycar. They have lots of sidewall to help with traction.


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## Jim H

Feathermerchant said:


> He swapped tire and wheel sizes making it much more difficult to compare. I was referring to overall tire diameter. Of course you should always use the smallest dia wheels as they are lighter. Even though the tire for the smaller diameter wheel has more rubber, rubber is less dense than aluminum. So the overall combo should be lighter. Besides look at a dragster or funnycar. They have lots of sidewall to help with traction.


Yes this video shows comparing 21" tires/wheels to 19" tires/wheels. In order to compare results you have to swap from one to the other. A shorter tire to a taller tire, which I believe was the question. Only way to compare I know of.
The video does show the affect of this when you compare the time slips. Taller tire had better trap speed and slower et, shorter tire had quicker et but slower trap speed. Not a big difference, but answers the question.
The question was which offered improved acceleration, a larger or smaller diameter tire. The video did show an improved acceleration with the shorter tire. 
Not sure how many tire choices there are for a 10,000hp Funny Car, but that was not the question. As far as traction goes it really boils down to tire compound. 200tw tire does better than 500tw for traction, unless there are freezing temps to deal with. Tire sidewalls have more affect on tire response and ride quality. 30 series tire more responsive than a 50 series tire.


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## Feathermerchant

But didn't the taller tire have a heavier wheel? Wouldn't that result in lower trap times and raise trap time in general?
Regarding sidewall height - I thought that drag racers agreed that lots of sidewall can get you more grip when used properly assuming the same tread compound and track conditions.
I know, an ICE has fewer but much larger torque pulses which tend to break the tire loose compared to an electric car. So sidewall may not be as important to us.


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## Jim H

Feathermerchant said:


> But didn't the taller tire have a heavier wheel? Wouldn't that result in lower trap times and raise trap time in general?
> Regarding sidewall height - I thought that drag racers agreed that lots of sidewall can get you more grip when used properly assuming the same tread compound and track conditions.
> I know, an ICE has fewer but much larger torque pulses which tend to break the tire loose compared to an electric car. So sidewall may not be as important to us.


Yes a lighter weight combination helps with acceleration, which was not addressed in this video. Personally I believe a light 18" wheel +35 with a 255/40 or 255/35 tire would be a good all around choice.
Top fuelers sidewall flex is quite amazing to see. The tire actually absorbs some of the torque produced, and is bolted onto the wheel to keep it from slipping on the wheel. It's all part of the torque management, along with clutch slippage and who knows what else. Plus they run low air pressure to help with the traction. Drag radials use some of the same ideas. 
Our cars traction control systems, especially with the AWD, works quite well. So much so even the MMX tires hook up to give great traction on starts. Shorter sidewall usually mean stiffer, for better response, but usually worse ride quality. That will be what I consider when replacing my MMX's.


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## Feathermerchant

I have the Performance model with 20" wheels and PS4S 235/35 20's. I replaced the tires and wheels with 18" +35 Titan 7 forged and 245/45 18 Michelin Primacy MXM. Won't spin on dry pavement. Better ride, better handling on bumpy curves, a little resonance due to no foam inside, steering response is more damped, less darty. Overall I like the tires better. Esp because I can drive them in cold weather. The PS4S would be great for a not too serious track day.


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## cali_wete

How's the tire noise of Michelin Pilot S4S compared to MXM?


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## Feathermerchant

The MXM I bought have no foam in them so I do get the ringing sound on certain pavement patterns. Other than that, they are quieter for my 20" -> 18" conversion. The size change may make a difference. Overall I am very happy. If/when I track, I'll get another set of light 18" and lower profile track (Sport Cup?) tires. That could lower the car a little as well.


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## Ole1

"Very noisy" ... I wouldn't be bothered at all (I am a loud pipes save lives kind of sportbike rider) .... but my wife didn't like them at all - when I had them on the car for a couple days for my last evening at the track ....


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