Aluminium Wheels vs Areodynamic Hubcaps
 

Hi Guys,
Currently have 16" x 6.5" wheels and they're steel. I was thinking about buying aerodynamic moon caps that seem pretty popular here. There is probably also a significant benefit by getting aluminum wheels. Has anyone tested this which is the better option?

There will probably be a weight difference of about 50-100lbs. Which is always nice but I haven't seen any aluminum wheels that have hubcaps. Unless anyone has any ideas there are the choices I see.

Aluminum 16" wheels - Save weight

Aluminum 18" wheels - Lower the RPM of engine at highway speed
Save weight

Aerodynamic hubcaps - Est 5% based on other people guesses on this forum.


Any ideas?

Less weight will enhance in-city mileage slightly where mass dominates.

Wheel covers will enhance highway mileage where aero-drag dominates.

Just wondering if anyone has run into this problem before. Seems like everyone goes with The covers. That is also the cheapest option.

As suggested depending on your route parameters. I have aluminum rims and they're just as easy to place wheel covers on as steel rims with covers.

Lighter wheels will only make a noticeable difference if you drive 30 feet, stop drive 30 feet, stop and do that all day. Like a mail truck.
If you drive at speed like a normal person, moon caps or aero OEM hub caps are the way to go. Plus they will only be a fraction of the price of a new set of aluminum wheels and a fraction of the price of a used set too.

Unless you're talking about buying very expensive forged wheels, the assumption that alloy wheels will save weight is often faulty.

OEM alloy wheels are much thicker than steel (because of the fatigue characteristics of alluminium), and will often end up heavier.

I swapped my factory 16" alloys to OE 14" steelies and saved 1.5kg per corner.

It's not helped by the fact that while your steel wheels are 6.5" wide, you'll probably struggle to find much in the aftermarket that isn't at least 7-8" wide.

Wheel size doesn't dictate tire size, it only changes your options. You could stick with your existing wheels and get taller tires if you wanted.

Plenty of people cut circles out of coroplast and zip tie them to their wheels, so you're not really limited by the wheel design.

What kind of car do you have?

Something that nobody has mentioned to take into consideration, Reduction of unsprung weight will reduce rolling resistance

This. Reduction in RR is good for mpg gains across the board, irregardless of driving.

I'll add my own $0.02. One of the mods I have done to my car is lighter wheels. My stock ZX2 steelies were heavy, I'd have to say upper teens since the 14x4 spare wheel by itself was 16-17 pounds. I replaced the stocks with Mazda MX-3 alloy wheels I got for cheap ($110 with low tread tires!) They weigh 12.5-13 pounds, and have been covered in coroplast covers for over a year. They have provided gains in FE, aero and RR, though all I have is anecdotal evidence and your trust of my word. I have a thread somewhere where I tested the MX3s against the spares in real world driving... let me try to dig it up.

I looked at getting lighter wheels like this - they would help constantly. They would give lower RR during acceleration, cruising and coasting. Every stop sign and traffic light I get caught at and have to accelerate from, the lighter wheels are requiring less fuel to get back up to speed. The only downside is cost. But there are deals out there such as my MX3 wheels for $27.50 a piece, and then selling the steelies for $65 for a grand total of $45 :)

I say go for both if you can!

Tell us what you're driving and we can make better recommendations for you :thumbup:

There are a lot of options for efficient alloy wheels, depending of course on your vehicle.
Switching from summer alloy wheels to winter steel wheels I notice my car feeling sluggish in town, my winter tires are lrr snow tires so I don't see a mileage drop on the highway, just on town.

Look for wheels from a hybrid, not aftermarket egg beaterwheels.

I have a mazda 3 2015 model.
I have a 5-10 minute drive to work, I stop 7 times in 1.5 miles. I'll say every 300meters. I drive home once a month 500 miles round trip. I currently get around 50-53 mpg on highway with a partial front air dam, and I removed the mud flaps.

I was thinking about larger wheels because, I eventually plan to add solar panels and remove the alternator. I figure at a given RPM there would be significantly less resistance than stock, so it would benefit by lowering the rpm and thus internal resistance primarily on the highway in 6th gear, since a transmission swap on a new car is pretty dumb.

I'll look into buying used alloy wheels and building coroplast covers. I also wanted to cover the rear wheel wells, but I don't really have the skills for that, I wouldn't know where to start.

A picture of the coroplast wheel covers would be great, I'll search the fourm first though.

Larger wheels will definitely reduce your highway RPM, but will also (likely) have larger rotating mass. I would imagine that, if you wanted to increase your overall diameter, you're likely better off going with taller tires and smaller rims, because metal weighs more than rubber. You'll probably come out ahead overall, but I'd suggest you keep in mind that your speedometer and odometer will read incorrectly if you go up or down in overall diameter.

Help's a comin'!
 

I'll start with the bolded section.
http://i0.kym-cdn.com/photos/images/...23/007/f29.png
(No disrespect meant, just a good opportunity to use a meme:D)

In all seriousness, engineering rear skirts is fairly simple. I'll dredge up my post when I made them for my ZX2.
http://ecomodder.com/forum/showthrea...tml#post476484

The hardest part of this is mounting the tabs and bar flush. The aluminum bar will have to be bent to accommodate your wheel well and tire, as most vehicles do not have the tire inset enough to make it flat. A slight bend will not hurt your Cd though.

A pic of a car similar to yours for reference:
http://www.web2carz.com/images/mmy/2...01_700x467.jpg
It looks like rear fender is setup like my ZX2 with the backside of the wheel well dipping behind the tire.
http://www.curbsideclassic.com/wp-co...1/Escort-2.jpg
You should be able to bend the bar as to not contact the tire while still being close to flush with the body.

Your route, is there another option? Those stops will be dragging down your FE pretty badly. If they are lights, try to time them the best you can. If they are stop signs, I suggest a new route with as few of stop as possible while keeping the distance comparable.

If I were you I would not look for bigger wheels. You already have a decently big tire on your car if it is the stock 205/60R16 @ 25.7". In fact, your car is better geared for the highway than my automatic ZX2! I plugged in the numbers on a gear calculator and you have ~9.4% higher gearing than my car, and this is very unheard of from most manual transmissions. For everyone's info, the 2015 Mazda 3 has a 0.68 6th gear with 3.85 final drive, from here.

For instance, @ 45 mph, you will be turning 1540 rpm in 6th while I am at 1700 rpm in 4th W/ TCC. Impressive!

I would try to find lighter 16's to save your current tires and keep from buying new tires, and when they wear out, go with a slightly thinner, slightly taller tire if you desire, such as a 195/65R16 or 195/70R16. Make sure they are LRR though, less energy = better mpgs!

Lastly, My thread linked above has pictures of coroplast wheel covers. They were quickly made in less than 2 hours, then painted and zip tied on. 15,000 miles later, they are still doing the job well. Aesthetic leave something to be desired, so I am going with custom painted pizza pans soon :)

Link for the coroplast wheel covers - http://ecomodder.com/forum/search.php?searchid=2413364

anyone
 

GM came up with this solution for their 100-mpg Ultralite of 1991.I'm not sure if it's a wheelcover,or a wheel with lug nuts concealed beneath the center cap.
Might be worth some research.
http://i1271.photobucket.com/albums/...ad2/02-072.jpg

Double check me, but it looks like 2006 and newer civic hybrid wheels would fit, Honda accord hybrid wheels should fit too.
Civic hybrid wheels are already smooth and light weight.

That's what I was thinking, but I'm pretty sure they're all 15"? With taller tires they'll work, of course.

There seems to be some confusion going on. First, afik, aluminum wheels of a decent quality, will almost always be lighter than steel wheels of the same size.

Next, larger diameter wheels do not necessarily imply a larger rolling diameter! They will however, be heavier than wheels of a smaller diameter and, more importantly, have a larger rotational moment of inertia. For example, my stock RX-8 wheel diameter is 18" and tire size is 225/45x18 which gives 800 rotations/mile. If I wished to improve mpg's by reducing rpm at a given speed, I could use a 235/50x18 to get 760 revs/mile. Or, keeping the stock overall gearing, I could go to a 17" wheel and use a 235/50x17 or 215/55x17 and get a lighter wheel assembly. One could go even further with a 225/55x16 tire/wheel assembly and still be pretty close to stock gearing.

For mpgs, one is overall much better off with a small diameter wheel and a "tall" tire. The rim is the densest component, so moving that inwards (even with the same weight) reduces the moment of inertia. Additional advantages include smoother ride and increased resistance to blow-outs from rough roads. Also, tires with taller sidewalls are easier to make and generally cheaper. Disadvantages include reduced maximum cornering limits and "sloppy" handling.

All the data is available for each tire model on Tirerack.com under the "specs" headers.