To Wheel Cover, or Not to Wheel Cover...

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BTW, Congrats on your new 2011.

For the Gen III, I prefer the look of the thicker spokes on the plastic cover as opposed to the smaller looking alloy. I hate that they're plastic, but they remain.

 

I'm with 32k and J5A. The alloys under the covers on the Gen III just don't look right.

The 16" Touring rims from Gen II are in a class of their own. Possibly the best move Toyota last made in the wheels category. 7 spoke gunmetal rims at 15.2 lbs each. They don't compare to anything that isn't aftermarket.

You can keep debating which way the 15" wheel looks better - covers on or off. Quite frankly I feel sorry for all of you w/o these 16" rims, that even includes you guys with the 17" V wheels, which I think weighs in at 22 lbs.

 

No worries, save your pity. I'll take better mpg and so-so wheels any day!!

 

Lol bro, you're not even right.

Gen II
15": 14.3 lbs
16": 15.2 lbs

Gen III
15": 16.3 lbs
17": 24.2 lbs

So I'm getting better mpg (in theory) and better looks. If the hypermilers here had brains (and money to waste haha) they'd be snapping up Gen II wheels, realizing they are actually more of an engineering feat.

 

That's not correct either. Weight is not a big factor in fuel efficiency. Rather, it affects acceleration/deceleration to a much larger degree. Increased rolling resistance (caused by larger wheels especially with wider tires) plays a much bigger role than unsprung weight in mpg hit.

 

I thought I covered my nice person with the "(in theory)" bit.

 

Sorry, I was unclear. I've never driven Gen II, but from what I read here and from the EPA ratings I gather the Gen III's are good for a few more mpg than the Gen II's.

So to restate, I'll happily accept the Gen III with its so-so, slightly heavier wheels to get more mpg than I could get in a Gen II. I bought the car for fuel economy, definitely not for aesthetics. But yes the Gen II 15" wheels would be even better if they would fit?

(FWIW, The Insight-I OEM tires weigh 11 lbs and the wheels weigh an additional 11lbs)

 

Gotcha. Yeah the Gen III is a newer, better car than Gen II, so better overall mileage for sure. I don't know how it works, I'm not a tech guy, but something about Hybrid Synergy Drive is improved.

(Yes Gen II wheels fit Gen III.)

 

True, so the larger tire might cancel out the lighter weight of the Gen II's 16" alloys compared to Gen III's 15". Weight isn't everything.

 

Exactly. In terms of rotational inertia, mass further from the axis of rotation (the axle) has a bigger effect because the mass is multiplied by its distance from the axis. So a lighter tire has more effect than a lighter wheel (of course it's best to have both as light as possible).

Given that the overall diameter of the wheel/tire assembly is the same, what we are doing is changing the mass distribution between the wheel and the tire, and maybe changing total mass as well.

If you do a lot of accelerating and decelerating, changes in rotational inertia will have an effect. One of the goals of hypermiling is to minimize unnecessary/random speed changes.

Wider tires may have increased rolling resistance, depending on which tires are being compared. Unfortunately the current "LRR" designation has about as much meaning as "free range chicken" as far as I can see.

A wider tire will also increase wind drag of the tires. Probably a small effect but maybe detectable.

 

Another affect of greater wheel weight is the force needed to turn the wheel at speed. I think lighter wheels are an issue for road racers, mostly.

That being said, I have mine off since the plastic ones chip and fray around the edges if you just look at them funny. Without hitting any curbs (so they might have been delivered that way) mine were all breaking around the edges, so I took them off.

I think any mileage savings from the plastic uglifiers is in the nature of a hillbilly "go-faster" as we used to say in the trade, when people put all sorts of uglifiers on their cars to make them look faster. Just a placebo.

 

Maybe they've determined that the wide spokes provide less side aero drag in wind tunnel testing and decided to go with that, thereby canceling out the slight weight gain in terms of mpg hit.

 

But is it the weight of the wheel or the width of the tire that effects MPG? I hate the 15" OEMs on my 2010 II. If upgrading to 17" yields a 0-5 mpg hit, I don't mind. I was getting 20 mpg on the highway with my Xterra. Anything above 30 mpg and I am in heaven.

 

It is primarily the rolling resistance of the tire. The weight doesn't amount too much. Worst case it's the equivalent of adding twice that weight to the inside of your car.

 

What I've noticed is that the 15" wheels look better with covers off when rolling, but better with wheel covers standing still.