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Do you or anyone out there know what the minimal rim size is that could be put on the nonPP spec? and for the PP spec?

I just spoke with the Martian Wheels guys and they're willing (potentially excited?) to put together options for the Polestar, especially as Spaces are opening up in the US, particularly in Denver where they're HQed.
What I need to get to them are the minimum rim size allowed and also what designs we'd like. I pointed them to the Polestar website and I basically said to clone those (as much as copyright allows...)

Or, any thoughts on how I could make the relevant measurement myself? Guessing they would want more exact numbers but I'm happy to give it a go.

The only thing that matters here is that massive Brembo caliper, maybe we can even find the specific cross section CAD graph or ask about it from Brembo?
The best racing wheels are said to be able to clear 380mm six piston Brembo caliper with 18 inch wheels and the Brembo brake on PP is a 375mm so I guess it should be possible?
For non-PP if we continue this line of thinking I guess we can have 17 inch wheels on them
 

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You might be able to measure delta values which, when combined with the OEM specs will give them what they need. Ie, how much clearance do you have between your current wheels and the calipers?
 
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Any enthusiast out there happen to have these measurements for the nonPP and the PP specs?

3867
 

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Any enthusiast out there happen to have these measurements for the nonPP and the PP specs?

View attachment 3867
Found a friend who likes to wrench and had all the proper tools (i.e. torque wrench, jack stand) and seemed excited to help me out. He just wanted a spin in the car. As a kind of upside, that spin itself seems to have convinced him to look at EVs. This is a guy who custom ordered a naturally aspirated V8 Lexus since he figured it was the last of those they would make. And he's now fairly convinced an EV will be his next one.

Here's are the stats I got, using the labels on that pic. In general I rounded up the numbers. I didn't exactly have highly precise measurement tools but this is what I got:

Front left tire/wheel:
weight: 57.6 lbs
A - 19.5 cm
B - 10.5 cm
C - 20.6 cm
D - 11.5 cm
E - 2.5 cm
F - 1.2 cm

Rear left tire/wheel:
weight: 57.5 lbs
A - 19.4 cm
B - 15.5 cm
C - 20.6 cm
D - 12.5 cm
E - 1.3 cm
F - 1.2 cm

Am fairly sure these numbers would be the same for the 20" nonPP spec. If anyone has a PP car and could measure and post those numbers (not to call out but, @ProfessorCook ??) that would be awesome.
The tires I have on are listed at 25 lbs, meaning the wheel itself is at least 30 lbs. [Although was surprised front and back measured the same... I thought rear rim wa 1" wider than front?]
Martian wheels claims that their rims' weights are 18-20 lbs depending on exact spec. Dropping 10 lbs per corner would definitely yield some lightness of the handling. And a lower profile rim/higher sidewall tire should yield a more smooth and less noisy ride.

I estimate we could indeed get 17" on the nonPP. Now I'm trying to decide if that would be fine or if it would look goofy.
 

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Found a friend who likes to wrench and had all the proper tools (i.e. torque wrench, jack stand) and seemed excited to help me out. He just wanted a spin in the car. As a kind of upside, that spin itself seems to have convinced him to look at EVs. This is a guy who custom ordered a naturally aspirated V8 Lexus since he figured it was the last of those they would make. And he's now fairly convinced an EV will be his next one.

Here's are the stats I got, using the labels on that pic. In general I rounded up the numbers. I didn't exactly have highly precise measurement tools but this is what I got:

Front left tire/wheel:
weight: 57.6 lbs
A - 19.5 cm
B - 10.5 cm
C - 20.6 cm
D - 11.5 cm
E - 2.5 cm
F - 1.2 cm

Rear left tire/wheel:
weight: 57.5 lbs
A - 19.4 cm
B - 15.5 cm
C - 20.6 cm
D - 12.5 cm
E - 1.3 cm
F - 1.2 cm

Am fairly sure these numbers would be the same for the 20" nonPP spec. If anyone has a PP car and could measure and post those numbers (not to call out but, @ProfessorCook ??) that would be awesome.
The tires I have on are listed at 25 lbs, meaning the wheel itself is at least 30 lbs. [Although was surprised front and back measured the same... I thought rear rim wa 1" wider than front?]
Martian wheels claims that their rims' weights are 18-20 lbs depending on exact spec. Dropping 10 lbs per corner would definitely yield some lightness of the handling. And a lower profile rim/higher sidewall tire should yield a more smooth and less noisy ride.

I estimate we could indeed get 17" on the nonPP. Now I'm trying to decide if that would be fine or if it would look goofy.
A big problem with running 17" is that to keep the diameter of the entire wheel set within +-2.5% range of the original we will have really wacky sizes like 245/55R17 which I took a brief look and it doesn't look optimistic on the availability end?

I had a look around and had a feeling that for optimal tire availability (winter + summer) and range and performance it would be better to have 8.5" rear wheel while downsizing the wheel to 18". I suspect the elimination of the staggered setup would have minimal impact on the acceleration performance since Model 3 had more torque with narrower tires although longer wheelbase so less load transfer I guess but doesn't seem huge, also P*2 AWD is biased towards rear? That's the real tricky part because things like this can in no way be measured.

I am thinking of these setups:
Front 18" 8.5" +50 offset
Rear 18" 8.5" +42 offset
255/45R18 or 235/50R18

Would your friend mind measuring the scrub radius of the front wheel though? Had P*2 have negative radius we would absolutely not want to ruin that

There's youtube video for people who had Martian 18x7 and it was 20+ lbs I don't think they can reach 20- with polestar wheels though given the unusually high offset stock wheels had, but using te37 as a reference it would still be 18-19 lbs
 

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A big problem with running 17" is that to keep the diameter of the entire wheel set within +-2.5% range of the original we will have really wacky sizes like 245/55R17 which I took a brief look and it doesn't look optimistic on the availability end?

I had a look around and had a feeling that for optimal tire availability (winter + summer) and range and performance it would be better to have 8.5" rear wheel while downsizing the wheel to 18". I suspect the elimination of the staggered setup would have minimal impact on the acceleration performance since Model 3 had more torque with narrower tires although longer wheelbase so less load transfer I guess but doesn't seem huge, also P*2 AWD is biased towards rear? That's the real tricky part because things like this can in no way be measured.

I am thinking of these setups:
Front 18" 8.5" +50 offset
Rear 18" 8.5" +42 offset
255/45R18 or 235/50R18

Would your friend mind measuring the scrub radius of the front wheel though? Had P*2 have negative radius we would absolutely not want to ruin that

There's youtube video for people who had Martian 18x7 and it was 20+ lbs I don't think they can reach 20- with polestar wheels though given the unusually high offset stock wheels had, but using te37 as a reference it would still be 18-19 lbs
Dammit - I had a feeling I should've posted "wheels off, what measurement's y'all want??" before remounting and tightening everything back up.
Did not measure the scrub radius. Let me see if I can get that from Volvo when I (hopefully eventually) get my random click noise looked at.

In terms of sizes, I agree, I can't find much to match the current diameters with 17". Also, now that I'm used to 19", I kind of wonder if 17" would look off - aesthetics amirite?
I was looking at 245/50R18 if sticking to 18" and it seems there're decent tire options at that spec - e.g. Michelin Primacy Tour A/S (though max rim width 8.5").

Although I fully admit to not fully grokking the pros/cons of all the specs and considerations.
Right now our widths/offsets (for both 19" and 20") are front 8"/50 and rear 9"/53, with 245mm width for both specs.
I was a bit tempted to go down on width (eg 235mm) to lower contact patch and improve efficiency, but not sure how that might pan out?
What's the upside/downside to maintaining the current staggered vs a square setup?
And what's the upside/downside of different offsets here?

Edit:
Keeping overall diameter about the same (current 27.7") I see these sizes (bolding the near exact matches):
17": 225/60R17, 235/55R17, 235/60R17
18": 215/55R18, 225/55R18, 235/50R18, 235/55R18, 245/50R18, 255/45R18, 265/45R18

And tires with good ratings and XL loads/high speed ratings in those sizes:
Vredenstein Quatrac Pro (225/60R17, 225/55R18, 235/50R18. 235/55R18)
Michelin Primacy Tour A/S (245/50R18)
Michelin CrossClimate+ (not CrossClimate2) (225/60R17)
Michelin Pilot Sport A/S4 (235/50ZR18, 255/45ZR18, 265/45ZR18)
Pirelli PZero A/S (245/50R18)
 

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Dammit - I had a feeling I should've posted "wheels off, what measurement's y'all want??" before remounting and tightening everything back up.
Did not measure the scrub radius. Let me see if I can get that from Volvo when I (hopefully eventually) get my random click noise looked at.

In terms of sizes, I agree, I can't find much to match the current diameters with 17". Also, now that I'm used to 19", I kind of wonder if 17" would look off - aesthetics amirite?
I was looking at 245/50R18 if sticking to 18" and it seems there're decent tire options at that spec - e.g. Michelin Primacy Tour A/S (though max rim width 8.5").

Although I fully admit to not fully grokking the pros/cons of all the specs and considerations.
Right now our widths/offsets (for both 19" and 20") are front 8"/50 and rear 9"/53, with 245mm width for both specs.
I was a bit tempted to go down on width (eg 235mm) to lower contact patch and improve efficiency, but not sure how that might pan out?
What's the upside/downside to maintaining the current staggered vs a square setup?
And what's the upside/downside of different offsets here?
Yeah... Basically 18x9 is so different than 19x9 or 20x9 so it would probably be better to concede and run 18x8.5 (or even less) just for the tire option alone, otherwise you run 255/45R18 with winter tires really hard to find

I feel like with AWD in hand the impact of the tire width itself is not going to be very visible on things like 0-60 time but this is completely a guess. The real difference is that I think all high performance summer (low efficiency probably) tires options close to stock are 245+ and it seems no one runs 18 performance tires below this width. Problem is many low resistance tires also have load ratings and speed ratings well below the stock performance tires and that is one thing to look at, also with wheels too narrow I wonder if our 2000kg+ car weight would come into play, basically if the load on the tires exceed certain limit you lose grip instead of gaining it.

Do they have the advanced option to adjust speedometer within +-2.5% in the infotainment system? Nissan Leaf has this option.

We don't have like the motor torque curve so I don't know if reducing wheel set diameter could improve efficiency or decrease it. Drag force = 0.01648v^2 + 0.2109v + 34.52 (unit: lbf & mph)

Polestar said to have tuned the AWD system to be rear biased. I have no experience with the car at all but reviewers say it feels like BMW M series, which means oversteer

So understeer -> front wheels lose grip first and
understeer -> rear lose grip first
Wider rear wheels -> more grip in the back -> less understeer
(Even with the same set of tires on different wheels the 1" wider wheel gets around 0.5" width on the tire itself, may vary)

track width = distance between mounting surface - 2x offset, so less offset on the rear wheel will reduce the load transfer going sideways -> better grip on the rear wheels -> less understeer

Based on the unusual offset P*2 provides there is a chance that there is negative scrub radius in the front? so if we install too much offset onto front wheel it might reduce it or change it to positive
Almost all volvo FWDs have negative scrub radius basically to combat torque steer but also in the case described here:


It will also help.
 

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Do you or anyone out there know what the minimal rim size is that could be put on the nonPP spec? and for the PP spec?

I just spoke with the Martian Wheels guys and they're willing (potentially excited?) to put together options for the Polestar, especially as Spaces are opening up in the US, particularly in Denver where they're HQed.
What I need to get to them are the minimum rim size allowed and also what designs we'd like. I pointed them to the Polestar website and I basically said to clone those (as much as copyright allows...)

Or, any thoughts on how I could make the relevant measurement myself? Guessing they would want more exact numbers but I'm happy to give it a go.

The designs of all of P*2 wheels are probably the worst kind of wheels for aerodynamic efficiency according to this paper here:
 

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I think that's the biggest effect on range for the PP (like I have) over the other versions. If you look, the other wheels aren't as bad, I think.
This could be it. Model 3 sees a 4% difference in range with aero hubcap on vs. off, and the hubcap is not optimal according to this paper (the left wheel has fan outwards and the right wheel has fan inwards since the cap design was universal, which would probably create a tiny bit of a torque on the car itself under high speed). How much difference does PP have on range alone? Also does non-pp 20" wheels suffer performance loss? Tesla's own report says 15% difference on range from 18" to 20" alone on Model 3

My guess is that the wheel weight distribution contributes more to the overall performance loss on range and more so on acceleration since the performance tires which are 2lbs heavier each are pushed further away from the axle by a only negligibly lighter but bigger wheel
 

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@ForteStig Any thoughts on these? What load rating do we need per wheel?:

I'm definitely interested in designing an aero cap for our (current or eventual) wheels.

I think Martian Wheels seem to also be interested in helping out with this if do push forward with them. I think would need to be a cap (some sort of plastic?) since covering the air gaps with forged metal would probably add too much weight.

This paper is totally interesting! I guess a thick outer rim + fan in of the radial elements would be the most aero design? How much open space would we need to leave for brake cooling, etc?

And if Martian just wants to make wheels and not caps, but gave us the requirement measurements of their wheel, from a CAD/stl file designed to fit that wheel, how hard would it be to 3D print a particular set of plastic and then get clips to hold it onto the wheel?

If we don't go with new wheels, anyone have files including measurements of the current wheels to design aero covers around?
 

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@ForteStig Any thoughts on these? What load rating do we need per wheel?:

I'm definitely interested in designing an aero cap for our (current or eventual) wheels.

I think Martian Wheels seem to also be interested in helping out with this if do push forward with them. I think would need to be a cap (some sort of plastic?) since covering the air gaps with forged metal would probably add too much weight.

This paper is totally interesting! I guess a thick outer rim + fan in of the radial elements would be the most aero design? How much open space would we need to leave for brake cooling, etc?

And if Martian just wants to make wheels and not caps, but gave us the requirement measurements of their wheel, from a CAD/stl file designed to fit that wheel, how hard would it be to 3D print a particular set of plastic and then get clips to hold it onto the wheel?

If we don't go with new wheels, anyone have files including measurements of the current wheels to design aero covers around?
I tried but didn't find enough stuff to calculate the load rating requirement for P*2 but I do know that original TE37's load rating barely misses the requirement for Model S which is very similar, however somebody still ran it with no problem. (Some body ran it with Model X and is said to still be alive!) This however has even lower load rating so I am a bit worried, other than that this doesn't require re-drilling while most aftermarket wheels have to be re-drilled from either 112 or even 114.3, but has a much smaller offset which means the wheels will be a little bit more outwards. Running 8" on rear may be another concern. Also 0 chance of clearing those PP Brembos i think.

I am curious what level Martian can/is wiling to reach as well, getting them to come up with a wheel solution would already be huge.

The paper suggests the combination solution may be the way forward, but to me it seems require some extra thought before such conclusion can be made. After all the fan design and the outer rim design works in complete different ways and there is little analysis to that. We do see a lot of middle of the way design in the paper and they are all not as good.
 

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Just noticed that that paper was from investigators in Gothenburg and with a co-author from Volvo itself. So it's not like they don't know what needs to happen...smh
The lead author's thesis goes through things in more detail:

Martian says their wheels are rated at 2000 lbs load, higher than the load ratings of the tires we might put on there. I wonder how they've validated that load rating.
 

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I truly admire the work that has gone into the posts on this thread. But do you really want to strip so much cool from your car in order to go a bit further? Soon enough the P2 will be available in single motor versions, with smaller wheels, for much less money.
Sorry for stating the obvious in the presence of far superior intellects.
 

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I'll measure up those wheels when I get a chance, Polerad. Busy end of the month, though.
 
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I truly admire the work that has gone into the posts on this thread. But do you really want to strip so much cool from your car in order to go a bit further? Soon enough the P2 will be available in single motor versions, with smaller wheels, for much less money.
Sorry for stating the obvious in the presence of far superior intellects.
Certainly if the end result is going to be something as fugly as the Model 3 18" aero wheels then I'm out. Wouldn't do that to the Polestar!

My goals here are to get lightweight wheels with higher sidewall, more aero, and ideally no/minimal compromise on aesthetics.
Folks out there have claimed substantial (>10%) consumption improvements on Teslas when dropping a wheel size and using something as light as the Martian wheels with proper low rolling resistance tires. Slapping an aero cover on top of that in principle should do even better. In addition, folks have reported a smoother ride with less noise, presumable from the corresponding greater tire sidewall.

If my main persistent (non-software-related) concerns about the Polestar are range and ride quality, then doing something that has a decent shot at improving both seems worth it.
I'm still trying to decide how much cash I'm willing to blow to do this experiment. And if/how much hit on aesthetics I'm willing to take. Upside for the latter is the guy at Martian seems open to working with me/us on what we think would be good, so have some level of control over that in principle.
 

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Certainly if the end result is going to be something as fugly as the Model 3 18" aero wheels then I'm out. Wouldn't do that to the Polestar!

My goals here are to get lightweight wheels with higher sidewall, more aero, and ideally no/minimal compromise on aesthetics.
Folks out there have claimed substantial (>10%) consumption improvements on Teslas when dropping a wheel size and using something as light as the Martian wheels with proper low rolling resistance tires. Slapping an aero cover on top of that in principle should do even better. In addition, folks have reported a smoother ride with less noise, presumable from the corresponding greater tire sidewall.

If my main persistent (non-software-related) concerns about the Polestar are range and ride quality, then doing something that has a decent shot at improving both seems worth it.
I'm still trying to decide how much cash I'm willing to blow to do this experiment. And if/how much hit on aesthetics I'm willing to take. Upside for the latter is the guy at Martian seems open to working with me/us on what we think would be good, so have some level of control over that in principle.
I mean, if we are only talking about hubcaps, BMW designs are already pretty rad:
 

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I've got some information on the PP OEM rims. These are my best shot at the dimensions, but note that I'm using woodworking tools for measuring them.

Rear rims:

29 lbs 10 oz +/- 2 oz (29.6 +/- 0.1 lb)
Rim width, face of flange to face of flange: 251 +/- 1 mm (9.88 in)
Rim width, inside flange to inside flange: 228 +/- 2 mm (8.98 in) Note that the flanges are tapered, so the measurement is approximate.
Outside diameter (from flange tip to flange tip): 548 +/- 1 mm
Inside diameter, just inside face that faces inwards towards the center of the car: 498 +/- 1 mm.
Inside diameter, just inside of the faced hub: 466 +/- 1 mm.
Depth, face of rim to face of machined hub face: 180 +/- 1mm.
Offset: 54.5 +/- 1 mm.

Front rims:

27 lbs 12 oz +/- 2 oz (27.8 +/- 0.1 lb)
Rim width, face of flange to face of flange: 225 +/- 1 mm (8.86 in)
Rim width, inside flange to inside flange: 205 +/- 2 mm (8.07 in) Note that the flanges are tapered, so the measurement is approximate.
Outside diameter (from flange tip to flange tip): 548 +/- 1 mm
Inside diameter, just inside face that faces inwards towards the center of the car: 498 +/- 1 mm.
Inside diameter, just inside of the faced hub: 466 +/- 1 mm.
Depth, face of rim to face of machined hub face: 165 +/- 1mm.
Offset: 52.8 +/- 1 mm.
 

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I've got some information on the PP OEM rims. These are my best shot at the dimensions, but note that I'm using woodworking tools for measuring them.

Rear rims:

29 lbs 10 oz +/- 2 oz (29.6 +/- 0.1 lb)
Rim width, face of flange to face of flange: 251 +/- 1 mm (9.88 in)
Rim width, inside flange to inside flange: 228 +/- 2 mm (8.98 in) Note that the flanges are tapered, so the measurement is approximate.
Outside diameter (from flange tip to flange tip): 548 +/- 1 mm
Inside diameter, just inside face that faces inwards towards the center of the car: 498 +/- 1 mm.
Inside diameter, just inside of the faced hub: 466 +/- 1 mm.
Depth, face of rim to face of machined hub face: 180 +/- 1mm.
Offset: 54.5 +/- 1 mm.

Front rims:

27 lbs 12 oz +/- 2 oz (27.8 +/- 0.1 lb)
Rim width, face of flange to face of flange: 225 +/- 1 mm (8.86 in)
Rim width, inside flange to inside flange: 205 +/- 2 mm (8.07 in) Note that the flanges are tapered, so the measurement is approximate.
Outside diameter (from flange tip to flange tip): 548 +/- 1 mm
Inside diameter, just inside face that faces inwards towards the center of the car: 498 +/- 1 mm.
Inside diameter, just inside of the faced hub: 466 +/- 1 mm.
Depth, face of rim to face of machined hub face: 165 +/- 1mm.
Offset: 52.8 +/- 1 mm.
Thank you sir!
27lbs seems heavier than expected for a forged alloy wheel, or is my expectation off?
 

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I've got some information on the PP OEM rims. These are my best shot at the dimensions, but note that I'm using woodworking tools for measuring them.

Rear rims:

29 lbs 10 oz +/- 2 oz (29.6 +/- 0.1 lb)
Rim width, face of flange to face of flange: 251 +/- 1 mm (9.88 in)
Rim width, inside flange to inside flange: 228 +/- 2 mm (8.98 in) Note that the flanges are tapered, so the measurement is approximate.
Outside diameter (from flange tip to flange tip): 548 +/- 1 mm
Inside diameter, just inside face that faces inwards towards the center of the car: 498 +/- 1 mm.
Inside diameter, just inside of the faced hub: 466 +/- 1 mm.
Depth, face of rim to face of machined hub face: 180 +/- 1mm.
Offset: 54.5 +/- 1 mm.

Front rims:

27 lbs 12 oz +/- 2 oz (27.8 +/- 0.1 lb)
Rim width, face of flange to face of flange: 225 +/- 1 mm (8.86 in)
Rim width, inside flange to inside flange: 205 +/- 2 mm (8.07 in) Note that the flanges are tapered, so the measurement is approximate.
Outside diameter (from flange tip to flange tip): 548 +/- 1 mm
Inside diameter, just inside face that faces inwards towards the center of the car: 498 +/- 1 mm.
Inside diameter, just inside of the faced hub: 466 +/- 1 mm.
Depth, face of rim to face of machined hub face: 165 +/- 1mm.
Offset: 52.8 +/- 1 mm.
Wait, this is crazy, so the actual offsets are rear 54.5 front 52.8(53)?

Thank you sir!
27lbs seems heavier than expected for a forged alloy wheel, or is my expectation off?
I think higher off set design have to strengthen the outer rim so it can cause a bit of weight more than expected.
 
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