Implications of 18" tires? Which rims should I choose?

[riddles]

Hey all,

Long time lurker here, but don't really interact much. I have read some threads and topics, but I am not sure what direction to go as I know I will need new tires soon.

I want to purchase the Hankook iON evo SUV tires and would also like to go down to 18" rims as I drive ~130 miles a day (highway) and want to get the best efficiency. I have also thought about getting the Rotiform wheels with the Aerodisc but every rim website says that they are not compatible with my Mach-E. Any advice here? Or should I just get some cheap compatible 18" rims?

For reference, I have a '22 Mach-E Select AWD.

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[GreaseMonkey]

Hey all,

Long time lurker here, but don't really interact much. I have read some threads and topics, but I am not sure what direction to go as I know I will need new tires soon.

I want to purchase the Hankook iON evo SUV tires and would also like to go down to 18" rims as I drive ~130 miles a day (highway) and want to get the best efficiency. I have also thought about getting the Rotiform wheels with the Aerodisc but every rim website says that they are not compatible with my Mach-E. Any advice here? Or should I just get some cheap compatible 18" rims?

For reference, I have a '22 Mach-E Select AWD.

Why don’t you install the new tires on your existing OEM wheels? They are 18”, right?

 

[riddles]

I have the 19” rims, so I would like to drop down to 18” for better efficiency.

 

[ArthurDOB]

Forgive my ignorance about tires, but I have always wondered what the difference would be in moving to 18" tires from 19" tires (other than "1 inch" ? ).

Why would that matter? How does that change impact efficiency?

 

[Coffs]

Both the 18" and 19" wheels use 225 width tires so there is no benefit in going down a size from a change in road surface friction (same width = same friction to overcome). The only benefit would be if the 18" wheels are lighter so you get very slight reduction in mass.
I have the exact same car and ok, in the summer i'm seeing 240 mile range at 70 to 75mph, I'm sure in Winter it's much less.
How much are you expecting to gain?

 

[HuntingPudel]

There are not a lot of 18” wheels that would be as efficient as the 19” Select wheels you already have. Certainly, aftermarket wheels will be less efficient since the vast majority of them are an aerodynamic nightmare. If you can find a set of CA Route 1 wheels, those would be slightly more efficient than your stock wheels. A set of 2021 Select 18” wheels would be just a bit less efficient than those. ?‍?

 

[riddles]

Forgive my ignorance about tires, but I have always wondered what the difference would be in moving to 18" tires from 19" tires (other than "1 inch" ? ).

Why would that matter? How does that change impact efficiency?

Check out this video. It explains the math behind changing wheel sizes, including going up in size.

 

[riddles]

Both the 18" and 19" wheels use 225 width tires so there is no benefit in going down a size from a change in road surface friction (same width = same friction to overcome). The only benefit would be if the 18" wheels are lighter so you get very slight reduction in mass.
I have the exact same car and ok, in the summer i'm seeing 240 mile range at 70 to 75mph, I'm sure in Winter it's much less.
How much are you expecting to gain?

I am not sure about the total mileage expecting to gain. I go the same speeds as you and I charge to 90%. Start the day ~180 range and get home anywhere from 45-60 range, just depends on temp and wind it seems. The video I posted in a different reply shows a Model 3 would get an additional 17 miles of range from 19" to 18" alone (not including the advertised efficiency of the tire).

 

[riddles]

There are not a lot of 18” wheels that would be as efficient as the 19” Select wheels you already have. Certainly, aftermarket wheels will be less efficient since the vast majority of them are an aerodynamic nightmare. If you can find a set of CA Route 1 wheels, those would be slightly more efficient than your stock wheels. A set of 2021 Select 18” wheels would be just a bit less efficient than those. ?‍?

That is why I am looking at the Rotiforms with the Aerodisc. However, it says they are not compatible with my model (not sure why). I have seen them on others who have posted here though. If I could find the CR1 wheels I would go with those, but Ford charges an insane amount for them.

 

[GreaseMonkey]

That is why I am looking at the Rotiforms with the Aerodisc. However, it says they are not compatible with my model (not sure why). I have seen them on others who have posted here though. If I could find the CR1 wheels I would go with those, but Ford charges an insane amount for them.

Load limits of the wheels could be a factor. The mme is a heavy vehicle and many aftermarket options don’t meet the requirements. It is best to stick with OEM if you can. I bought a set of 19” takeoff wheels for a reasonable price for my premium and installed winter tires. Worked out great.

 

[MellowJohnny]

I'm with @HuntingPudel - those stock Select rims are already pretty efficient.

I'm assuming the quest for more range is based on saving both time & money, but I suspect after investing $1,000+ on new rims the payback will be long.

As an example, so far this year I've driven 30,000 km (circa 19,000 miles) and spent about CAD $600 (about USD $435) to charge, mostly at home, with a few DCFC and L2 changing thrown in.

Hypothetically if the efficiency gains amount to 5%, that equates to a savings of about $22 for the year. At that rate you break even in 45 years.

If you want to buy some fun new wheels, go for it! But I think if the goal is savings via better efficiency, I don't think the math makes sense.

 

[jay1122]

I think you are wasting your money changing the wheels or tires just for that little extra range. If your car's range is struggling to meet your daily commute need. You need to think more about reinvest in a long range EV like M3LR.

 

[riddles]

I'm with @HuntingPudel - those stock Select rims are already pretty efficient.

I'm assuming the quest for more range is based on saving both time & money, but I suspect after investing $1,000+ on new rims the payback will be long.

As an example, so far this year I've driven 30,000 km (circa 19,000 miles) and spent about CAD $600 (about USD $435) to charge, mostly at home, with a few DCFC and L2 changing thrown in.

Hypothetically if the efficiency gains amount to 5%, that equates to a savings of about $22 for the year. At that rate you break even in 45 years.

If you want to buy some fun new wheels, go for it! But I think if the goal is savings via better efficiency, I don't think the math makes sense.

It's not about the value or saving money. It is more about convenience. I want to be able to make my daily commute and still have the option to drive my car downtown that night if needed. Currently, I can't do that without having to charge because everything is highway miles.

 

[riddles]

I think you are wasting your money changing the wheels or tires just for that little extra range. If your car's range is struggling to meet your daily commute need. You need to think more about reinvest in a long range EV like M3LR.

I will need to replace the tires soon anyways. I am sitting at 5/32 at 18k miles. I won't do this until I need to replace the tires. But beyond that, I just want to have the option to drive more if needed without having to stop at a fast charger. I am satisfied with my MME and do not want to trade it in.

 

[GT_order_#1001]

Hello @riddles . I'm completing a wheel change similar to the one you're considering but on a 2022 GT. I work from home but when I drive it's mostly on the highway so vehicle speed, wheel aerodynamics, and tire choice and pressure are the key contributors to efficiency. The Rotiform R142 LAS-R 19x8.5 +45 will easily fit the GT (but not the GT-PE) brakes and will fit within the wheel wells similar to stock. The LAS-R is one of the few Rotiforms that can mount the Aerodisc.

Note that I'm going with 19" rims (down from the GT stock 20") and I'm mounting Conti ExtremeContact DWS06 Plus 245/50 tires. These are not "EV" tires so I'm getting great tires and slightly better ride quality but not an EV tire efficiency benefit. I'm countering that "inefficiency" by mounting Aerodiscs on all four corners.

My GT is Shadow Black w/tinted windows and the new rims and Aerodiscs will be black .. to create the "murdered-out" or Batmobile look I want. The look of the car is equally important to me as the marginal (3% - 6%?) gains in efficiency.

I can provide you my sources for the Aerodiscs and the new center cap hex nut & hex nut tool if you're going ahead with this project. The 19" LAS-R rim can't be found for less than $403 each (Rotiform apparently disallows discounting by its dealers). The 18" should be a tad less but I never looked into that rim size.

I hope to pick up the new wheels this weekend from my local Discount Tire (there's been a delay getting one of the tires). I'll post pics after everything is mounted.

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