OT: Wheels for cars, aero? Lightweight?

[Dave]

It's rim width that really determines the proper tire width. Most people go the opposite direction and use larger diameter rims with smaller aspect ratio. I can't imagine any significant difference in fuel mileage. Manufacturers need high mileage ratings listed on their new car stickers. Wheel setback is also important unless you want tires sticking out beyond the fenders.

I have a 2022 Tucson with 19 inch rims and a 2022 Santa Cruz with 20 inch rims and 235/245 tire widths, respectively.

The major tire sellers all have listings of the proper change in aspect ratio, if changing rim diameter.

My not-aerodynamic '37 hot rod with a modern fuel injected 430hp V8 had 295/45 back tires on 20x10 inch wheels. The engine ran the same 2100 rpm at 80mph, as my Santa Cruz. It got 23mpg on the highway and 19-20 in town.

[Likes2ridefar]

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[Mark McM]

Originally Posted by Likes2ridefar

Here I thought it was a joke and they did make them…and replicas are still available.

And in a related matter:

Campagnolo actually made the first disc brakes used on a production bike, all the way back in 1965. But the bike in question was not a bicycle, it was a motorcycle (the Lambretta TV125). (And in case you're wondering, they were cable actuated brakes.)

[4151zero]

Originally Posted by Likes2ridefar

Here I thought it was a joke and they did make them…and replicas are still available.

No joke!


https://www.bicycling.com/bikes-gear...lo-car-wheels/

[charliedid]

I have the same issue with 18" wheels on my TDI Sportwagen and some days I just want to trade the whole car in. Parking on the street is a nightmare for the wheels and tires not to mention the pot holes. I wished I had swapped these when I bought the car.

16" steel wheels seem to be in my future.

[Dave]

Originally Posted by Likes2ridefar

Let’s see a photo if you have one on hand

I only ran 26 psi in those rear tires.

[Likes2ridefar]

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[cgates66]

For highway driving, you will likely be disappointed with any mileage gains if you're expecting 15%.

Ca. 80% of the power is used for aero (where have I seen that before...) at 65 or so MPH (varies by vehicle many caveats apply), so only 20% is rolling resistance anyway.

You need to reduce rolling resistance by 75% to get a 15% improvement in mileage at highway speeds, which seems unlikely (that is, if you had 80% + 20% - 100%, you need to get to 80% +5% - or 15/20 need to go away).

Around town, there could be meaningful gains.

[Likes2ridefar]

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[CAAD]

I would look into getting the wheel repaired.

Wheels and tires will cost $1200 at the low end of the spectrum. $1200 to save a few bucks per full up. That's a lot of fill ups to break even.

[Ralph]

Yes....and fuel economy savings will be minimal. Your information of 15% poorer fuel economy with larger diameter wheels is not accurate.

[yinzerniner]

Originally Posted by Ralph

Yes....and fuel economy savings will be minimal. Your information of 15% poorer fuel economy with larger diameter wheels is not accurate.

Not necessarily true. While 15% might be in certain best case vs worst case scenarios, a lower percentage change of ~5% wouldn't be considered "minimal" in most cases.

Tesla explicitly states the range differences between their wheel and tire options.
And Car and Driver did a test a while back showing the difference between the different wheel/tire size combos. 225 width tires on 17/18 wheels yielded about 4% savings, so a 2" gap could be more of a percentage difference like the OP is thinking.

Both of the above are discussed here:
https://insideevs.com/news/375165/te...nge-tire-size/

Note on above - the tire width differences could also explain a bit of the range/mpg differences between the different wheel sizes, but the 17/18 comparison had the same width

[C40_guy]

Originally Posted by tylercheung

see if there's NOS Campagnolo wheels :P

I think I have a set of hub caps for those wheels. They are surprisingly small!

[Likes2ridefar]

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[NHAero]

I've used inexpensive steel wheels for mounted snows on my Hondas (Civics, VX, CRX, and Fits) for decades. Almost always I'm using a steelie one inch smaller in diameter to fit the snows and maintain clearance while aim8ng at the same overall OD. I haven't weighed them, but the steelies and snows usually seem lighter weight than the OEM alloys and the all season tires.