19" vs 21" Wheels Pros and Cons

[jerry33]

Good point, I hadn't thought of that. But still, another debunked idea still driving crazy behavior.
Perhaps they are members of the Flat Earth Society, too?

LOL. Given that something like 27% of Americans believe that the Apollo moon missions of the sixties were just filmed in Hollywood, there is little that surprises me. We have to do something about getting rid of superstition and promoting science education and critical thinking.

 

[pete8314]

I'm still torn over the wheels, I suspect my deciding point will be if I can somehow afford the P85 I'll get the 21s (the design of which I much prefer, I couldn't care less about the size), and if it's the S85, I'll stick with the 19's and save a lump of money.

The concern about scuffing them is valid, though compared to the UK where I lived more most of my life, the curbs here in the US and all curvy (rather than angry and sharp-cornered!) so I'm less worried than I would have been, although my wife did manage to completely mangle a wheel on her previous car (the exact circumstances were never really explained, and it was a fairly crappy Dodge wheel that cost $80 to replace!).

On the subject of potholes, I've lost 2 tires in the past year due to pot-holes, there's a lot of construction on my work route, that's essentially causing the existing road to separate, with wide, cavernous gaps. Both time, a wheel went down there, you get the depressing smell of burnt rubber, and the tire pressure warning pops up :-( These are 19" 255/35 tires, so on that basis, I'm not sure I'll be much worse-off with the 21s.

 

[smorgasbord]

These are 19" 255/35 tires, so on that basis, I'm not sure I'll be much worse-off with the 21s.

You'll be better off with 35 aspect tires on 21" rims than 35 aspect tires on 19" rims due to the greater sidewall height. Assuming same tire and wheel construction, of course.

I'm completely torn on what to do about wheels. I'm getting MSP - do I also get 19"? I can't see not at least getting the 21", if just for resale value.

What we really need to find is a good set of 20" aftermarket rims that work.

 

[jerry33]

You'll be better off with 35 aspect tires on 21" rims than 35 aspect tires on 19" rims due to the greater sidewall height.

It would be a mistake to put 35% aspect ratio tires on a 19" wheels on the Model S. The carrying capacity would be much lower (assuming the same nominal section width) and the gear ratio would be totally messed up. If you purchased wider wheels and wider tires then it might be possible but clearance would be a factor. In addition if you weren't able to get a wheel offset that would put the centre of the tire in exactly the same place as the center of the OE tire, then wheel bearings and other suspension parts will suffer.

 

[SCW-Greg]

Hey, all this talk aspect ratios, etc, but how do they calibrate your speedometer? I'm certain that the over all circumference is significantly different between the two. Or do they? Maybe the do that at the factory, but what about post delivery changes?

More than just the speedometer, this would impact range calculations and more.

 

[Tommy]

Hey, all this talk aspect ratios, etc, but how do they calibrate your speedometer? I'm certain that the over all circumference is significantly different between the two. Or do they? Maybe the do that at the factory, but what about post delivery changes?

More than just the speedometer, this would impact range calculations and more.

Specs for the Continental 21" and Goodyear 19" tire taken from Tire Rack:

Note the rotation of each tire needed to travel one mile: 750 vs 755, is virtually the same. Tesla uses the different tire aspect ratio for the different wheel rim sizes (19" & 21") to keep the circumference for all practical purposes identical.

 

[smorgasbord]

It would be a mistake to put 35% aspect ratio tires on a 19" wheels on the Model S.

Thanks for that non-sequitur.

 

[SCW-Greg]

Note the rotation of each tire needed to travel one mile: 750 vs 755, is virtually the same. Tesla uses the different tire aspect ratio for the different wheel rim sizes (19" & 21") to keep the circumference for all practical purposes identical.

Thx Tommy! Didn't think they would be that identical.

 

[jkirkebo]

You'll be better off with 35 aspect tires on 21" rims than 35 aspect tires on 19" rims due to the greater sidewall height. Assuming same tire and wheel construction, of course.

Nope, sidewall height would be the same for both rim sizes. The sidewall height is the tire width times the aspect ratio. 245/35-21 has a sidewall height of 245*0.35=85.75mm. 245/35-19 would have the exact same sidewall height but the tire diameter would be 2" lower. So to get the same diameter you would need a sidewall height of 85.75+25.4=111.15mm with the 19" tires. 245/45 is close, 245*0.45=110.25mm. If you want a 35 aspect ratio with 19" tires you need 111.15/0.35=317mm thread width. Can you even get 315/35-19 tires ?

 

[smorgasbord]

The sidewall height is the tire width times the aspect ratio.

Thanks for that clarification!

 

[xhawk101]

I would like to get the 19 in tire on the fan style wheel ...since not available I am wondering about aftermarket wheels from day 1. I can't find any discussion on this. Any suggestions?

 

[agileone]

I would like to get the 19 in tire on the fan style wheel ...since not available I am wondering about aftermarket wheels from day 1. I can't find any discussion on this. Any suggestions?

Been discussed here : Would you buy 19 inch turbine wheels?

I was thinking of getting Lorinser RS8 mentioned on page 2, but these are MB wheels, so it seems we will have to find similar wheels fitting a BMW wheel pattern.

 

[William13]

Alzor 621 looks good but is an Audi size. 19 inch . I await someone getting accurate wheel measurements with bore, offset, and bolt size.

 

[dsm363]

For sale post moved here:
21 grey factory wheels for sale in New York City

 

[VaG]

Now that the 21" wheels+tires are $4500, I am rethinking about the two ways to go. Has anyone tried to tally up the entire list of positives and negatives on the wheel sizes? Something like this (which for the sake of building the list, contains some guesswork on my part):

Acceleration is unaffected (according to manufacturer)


21"
Brand new set costs $4500
Four replacement tires cost $2000
Unsprung mass is higher, which hurts the suspension
Worse performance in snow due to wider tires
Worse performance on wet roads due to more water in the tread
More easily scratched on curbs
Rims more easily dented, tires more easily blown, on potholes etc.
Range is 5% shorter
Shorter braking distances
They look WAY cooler
Better cornering


19"
Brand new set costs ZERO
Four replacement tires cost $1000
Unsprung mass is lower, which helps the suspension
Better performance in snow due to narrower tires
Better performance on wet roads due to less water in the tread
Less easily scratched on curbs
Rims less easily dented, tires less easily blown, on potholes etc.
Range is 5% longer
Longer braking distances
They don't look as cool
Cornering isn't as good

 

[Oreo]

Now that the 21" wheels+tires are $4500, I am rethinking about the two ways to go. Has anyone tried to tally up the entire list of positives and negatives on the wheel sizes? Something like this (which for the sake of building the list, contains some guesswork on my part):

21"
Worse performance in snow due to wider tires

19"
Better performance in snow due to narrower tires

I hope you are not planning to drive on snow with anything BUT snow/wintertires?
So I think the above arguments you used regarding snow conditions are not valid.
Anyway you'd go for a separate set of tires for winter (or all season if very little snow?).
I'm going for a separate set of 19" with PROPER winter tires (not any "All-season" alternative), and a set of 21" Michelin PS2.

Of course I don't know what its like where you live, but where I live I have to use the winter tires half the year.
If you use common economical sense everyone would go for the 19".
If you don't necessarly bother about common sense, and the financial part, want a sporty drive etc. I think the 21" would be the option.
I can only speak for myself, I DO have to borrow money to finance my P85+, so not much "common sense" from my part. :love:

 

[WarpedOne]

I hope you are not planning to drive on snow with anything BUT snow/wintertires?
So I think the above arguments you used regarding snow conditions are not valid.

They are valid.
Wider snow tires need more pressure to brake the snow/water than narrow winter tires.

 

[Mark Petersen]

hmm

there is no difference in the width between the 19 and 21, they both come with 245mm
but the 21 can only use summer tires, where the 19 support both summer, all year & winter (I have not found any manufacturer of 21" winter tires / all season)
so if you drive in a region with snow, you can only use the 21 during the summer

 

[VaG]

Can't believe I didn't know the tires are the same width on both sizes. Proves I'm not doing my homework :| I don't think the 19's will be significantly different on snow, then, since narrow tires get the advantage (from what I have seen & read over the years)

I guess these parts should be stripped out -

Worse performance in snow due to wider tires
Worse performance on wet roads due to more water in the tread

And the first part changed to:

Same/not significantly different on both:
Acceleration
Performance on wet roads
Performance on snow

 

[hiroshiy]

Actually, when attached to the Model S body, 19 inch wheels make the car width (measured tire to tire) narrower by about an inch. That's one of the important differences and the reason why I chose 19.