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20" to 18" Wheels

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leweegi

New Member
Apr 27, 2020
2
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Brea
I have a 2019 Model 3 Performance. I love the car, but I am thinking about switching my wheels and tires to 18" to get better range and maybe a better ride. And after reading some posts re: wheel/tire damage from potholes - I want to go ahead with the switch. I am looking at T Sportline TSS 18" wheels and Martian MW03 8.5" wheels. The T Sportline wheels are "flow forged" and less expensive than the the Martian "fully forged" wheels. I am not sure that spending more really gets me a superior wheel. Does anyone have advice on this wheel/tire switch?
Thanks,
Jim
 
Same issue as you, went from 20'' wheels down to T sportline 18'' TST, used OEM MXM4 primacy tires, on normal freeway commute, I'm around 240 wh/mi (as opposed to over 300 prior).

Just to correct any people who think they're going to get 240Wh/mi with 18s vs 300Wh/mi with 20s, that's simply not going to be the case. Either your ambient temperatures have warmed up, you're keeping low mph on your travels, or you're not driving as aggressively, but... nope.
 
If you really care about the ride quality and range, I think you should definitely go with the 18".

I have a SR+, and it's one of the reasons why I went with the 18" aeros, I don't want to deal with potential wheel damage from potholes going for the 19" sport rims. Even with the 18" aeros, sometimes I feel more on bumps than my mom's honda civic which have 16" rims...
 
Just to correct any people who think they're going to get 240Wh/mi with 18s vs 300Wh/mi with 20s, that's simply not going to be the case. Either your ambient temperatures have warmed up, you're keeping low mph on your travels, or you're not driving as aggressively, but... nope.

I agree with WilliamG switching from 20s to 18s is not going to make that difference alone. A combination of other factors might make that big a change such as changes with wheel width, tire compound, or outside factors such as temperature.

Some other thoughts are:

The weight of your wheels directly affects acceleration and range so lighter is good. Everything else tends to be a trade off where you lose something like handling to gain something like range.

Generally the 18s will be faster off the line with the same tires but will not handle the corners as well. However those bigger sidewalls will protect you if you hit potholes and make the ride seem less bumpy.

Wider tires might handle better in the dry, but are not as good in wet or snow.
Skinnier tire width pays off big for range but are not as good for traction off the line or in corners, unless its snowing then they are preferred.

If you do hit a pothole and break a 20 in performance rim it will probably cost you north of 1500 when you are done.

So a lightweight fully forged 18 inch wheel would help some with range and reliability but you will trade off some on handling.
 
FWIW the Tesla document filed with the EPA for the 2020 Performance 3 shows a Road Load HP at 50 mph of 10.37 with 18” wheels and 11.98 with 20” wheels. This would be the factory wheel and tire configuration. Only their estimate (based on their testing), but probably has some relative meaning. Approximately 15% more power required to move the 20” tire version than the 18” tire version at 50 on a flat road...
 
FWIW the Tesla document filed with the EPA for the 2020 Performance 3 shows a Road Load HP at 50 mph of 10.37 with 18” wheels and 11.98 with 20” wheels. This would be the factory wheel and tire configuration. Only their estimate (based on their testing), but probably has some relative meaning. Approximately 15% more power required to move the 20” tire version than the 18” tire version at 50 on a flat road...

But that doesn’t take into account the rolling resistance as mentioned above. The PS4S (factory 20s) are very sticky tires with phenomenal performance and the Primacy MXM4s (factory 18s in America) are very...crappy tires (well, they’re basically just OK at what they do).
 
Also keep in mind your tire is the final “gear” In your drive system. The bigger the tire the more torque it takes to start and roll it. I guess that could have an affect on range, performance and maybe a little more stress on the motor. I like the looks of bigger tires and wheels but I’m sticking with the 18”.
 
Wider tires might handle better in the dry, but are not as good in wet or snow.
Skinnier tire width pays off big for range but are not as good for traction off the line or in corners, unless its snowing then they are preferred.
Educate me, please. Skinnier tires are better in snow, you say. That struck me as unexpected. Why is that true? I would have assumed more surface area would give more traction. Is it that a smaller contact area is more likely to "cut through" the snow and find pavement? Interesting.
 
Educate me, please. Skinnier tires are better in snow, you say. That struck me as unexpected. Why is that true? I would have assumed more surface area would give more traction. Is it that a smaller contact area is more likely to "cut through" the snow and find pavement? Interesting.
That’s my understanding. When I had my MINI, I ran skinnier snow tires than my summer tires. Kind of like having skis, the car would go where I pointed it better in snow with the narrow tires.
 
But that doesn’t take into account the rolling resistance as mentioned above. The PS4S (factory 20s) are very sticky tires with phenomenal performance and the Primacy MXM4s (factory 18s in America) are very...crappy tires (well, they’re basically just OK at what they do).
Actually an automaker is required to report their assumptions (RLHP) to the EPA based on actual testing of the vehicle configured in a way that it is sold. For 18” wheel vehicles it would include the factory MXM’s. For the 20” wheel vehicles it would include the factory PS4’s... Again the RLHP at 50 mph is just that. Doesn’t reflect the energy to accelerate, decelerate, overcome bumps in the road, etc.
 
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Actually an automaker is required to report their assumptions (RLHP) to the EPA based on actual testing of the vehicle configured in a way that it is sold. For 18” wheel vehicles it would include the factory MXM’s. For the 20” wheel vehicles it would include the factory PS4’s... Again the RLHP at 50 mph is just that. Doesn’t reflect the energy to accelerate, decelerate, overcome bumps in the road, etc.

I don't disagree with that. All I'm saying is you can't just say 18s are going to be that much better than 20s in terms of energy consumption when the 18s have the MXMs and the 20s have much sticker PS4S. It's not really a fair comparison. You either want PS4S or you don't. With the 18s + PS4S the numbers will be almost certainly much closer in terms of energy consumption.
 
just to chime in on my specific particular experience in more detail for anyone who may find this useful;

went from (over 300wh/mi)
• 20'' OEM wheels / Tires (Pilot Sport 4S)

to (249 wh/mi)
• tsportline 18'' wheels / OEM 18'' tires (Primacy MXM4)

this was as similar as can be normal freeway commute (90% of the driving was on the freeway, similar times, similar traffic situations, and not excessively running the heater or at major speeds above the rest of moving traffic), california / bay area winter and summers

it's a single data point for standard normal behavior, I'd also say likely in AP for over 50% of the time if that makes a difference

overall - it was the combo of the 18'' wheel and the OEM primacy tire that got me the 249 over the life of the car with the 18'' wheel set up, pic attached, no change in driving behavior (IE - extreme lead footing)

YMMV (also correction to my 240wh/mi above, 249wh/mi is what I'm averaging over 20K+ miles)
 

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just to chime in on my specific particular experience in more detail for anyone who may find this useful;

went from (over 300wh/mi)
• 20'' OEM wheels / Tires (Pilot Sport 4S)

to (249 wh/mi)
• tsportline 18'' wheels / OEM 18'' tires (Primacy MXM4)

this was as similar as can be normal freeway commute (90% of the driving was on the freeway, similar times, similar traffic situations, and not excessively running the heater or at major speeds above the rest of moving traffic), california / bay area winter and summers

it's a single data point for standard normal behavior, I'd also say likely in AP for over 50% of the time if that makes a difference

overall - it was the combo of the 18'' wheel and the OEM primacy tire that got me the 249 over the life of the car with the 18'' wheel set up, pic attached, no change in driving behavior (IE - extreme lead footing)

YMMV (also correction to my 240wh/mi above, 249wh/mi is what I'm averaging over 20K+ miles)

That makessense, but it wouldn't surprise me if the tires make more of a difference here than the size of the wheels. Does anyone have any data from 20s with PS4S vs 18s with PS4S on their own car?