[James Romeyn]

I'm naturally paranoid having spent years responding to fires/emergencies/car wrecks.  So even though I've got AWD I bought chains (Spike's Spider's Sport) for the drive from CA to UT (of course it was 60s & maybe low-70s & clear most of 800+ miles).

So I've got these hugely heavy lugnuts & mounting plate extensions on the front wheels now.  I intend to return the OEM nuts asap.  Meanwhile, being a huge time waster typing here instead of doing what I should be: I noticed kinda crummier than normal city mpg lately.  Could these very heavy nuts & extensions be contributing to my woes?  They might be 10x heavier than oem, maybe even greater.   

 

 

[Russell Dawkins]

I would say yes, slightly, and also spoiling your ride over rough pavement by making the unsprung weight ratio worse.

[James Romeyn]

Interesting point about the ride, am familiar w/ the effect from riding cycles.  I have noticed a slightly choppier ride than normal. 

Maybe I'll visit the tire shop down the block tomorrow.  They did an emergency tire rotation for me about a year ago during a visit (I forgot about rotating & the fronts were wearing funny; didn't want to add 800 miles of bad wear before the alignment).  They absolutley refused to take money, even after I insisted.  Try that in CA.

 

[EDS_]

I'm naturally paranoid having spent years responding to fires/emergencies/car wrecks.  So even though I've got AWD I bought chains (Spike's Spider's Sport) for the drive from CA to UT (of course it was 60s & maybe low-70s & clear most of 800+ miles).

So I've got these hugely heavy lugnuts & mounting plate extensions on the front wheels now.  I intend to return the OEM nuts asap.  Meanwhile, being a huge time waster typing here instead of doing what I should be: I noticed kinda crummier than normal city mpg lately.  Could these very heavy nuts & extensions be contributing to my woes?  They might be 10x heavier than oem, maybe even greater.   

A buddy who is big into auto racing claims the following relating to cars.....

One marginal pound of rotating mass equals forty-pounds of added body weight
One marginal pound of revolving mass equals seventy-three pounds of added body weight
One marginal pound of recipricating mass equals eighty-eight pounds of added body weight

He also says that different sources offer grossly different estimates regarding weight penalties.

[TomS]

I'm naturally paranoid having spent years responding to fires/emergencies/car wrecks.  So even though I've got AWD I bought chains (Spike's Spider's Sport) for the drive from CA to UT (of course it was 60s & maybe low-70s & clear most of 800+ miles).

So I've got these hugely heavy lugnuts & mounting plate extensions on the front wheels now.  I intend to return the OEM nuts asap.  Meanwhile, being a huge time waster typing here instead of doing what I should be: I noticed kinda crummier than normal city mpg lately.  Could these very heavy nuts & extensions be contributing to my woes?  They might be 10x heavier than oem, maybe even greater.   

A buddy who is big into auto racing claims the following relating to cars.....

One marginal pound of rotating mass equals forty-pounds of added body weight
One marginal pound of revolving mass equals seventy-three pounds of added body weight
One marginal pound of recipricating mass equals eighty-eight pounds of added body weight

He also says that different sources offer grossly different estimates regarding weight penalties.

Good observation and very true.  That's why the big +size wheels/tires (19's, 20's, 22's) reduce mileage (and handling beyond a certain point) - rotating mass is much much higher.  They are just plain heavy and that's not good.

[Bill Baker]

One marginal pound of rotating mass equals forty-pounds of added body weight
One marginal pound of revolving mass equals seventy-three pounds of added body weight

 This is very interesting as well as true. Being a suspension and alignment tech for almost 15 years, I have dealt with this a lot in the past as I have set up everything from race cars, large 4x4's as well as big rigs and fire trucks.

 What RS is dealing with here is One marginal pound of rotating mass equals forty-pounds of added body weight as the lugs are obviously on the same plain as the axle. While lug nuts are not very heavy to begin with, the additional rotating mass on front wheel drives has more effect on gas milage than rear wheel drive vehicles (even though it's an AWD).

 This is one of the reasons I never went with those huge rear tires on all the hot rods and muscle cars I've built in the past. I like to keep them low profile and use lightweight aluminum rims.

[Folsom]

Use the best functional lug nuts and it will equal decent weight I am sure. They are not an item to skimp on in case of an emergency when their ultimate strength gets checked.

However good tires and wheels to save a lot of combined weight is a good call. It will save you gas most certainly. During summer run rain/road tires that are firm and efficient, in winter (snow required to switch too) supple grabbing tires (not studs).

AWD is nice for traction unless you break loose with all four wheels under power, then anything can happen. Also AWD is unfortunately a bigger fuel burner. Simply there is more mass moving, and more energy lost through the connections of all of it, along with the extra mass. If you REALLY need the traction, like you travel on heavily snowed areas, we are talking like you drive through stuff that is a foot deep to your house, then by all means AWD is for you. However FWD will get around any normal city that receives snow, and is plowed. The trick is just in the supple tires, and not being a lead foot, etc... paying attention to the road. Plus there are options for some cars to get a form of limited slip put into a FWD car that makes them amazing for traction. Older RWD cars, or newer BMW etc with limited slip (more particular the heavier ones though) have traveled in winter since they were made back to whenever real cars started, in the 30s?

[James Romeyn]

I keep thinking nobody will care about this esoteric stuff, next thing techs who setup up race cars are chiming in...Neat!

That's why the big + size wheels/tires (19's, 20's, 22's) reduce mileage (and handling beyond a certain point) - rotating mass is much much higher.  They are just plain heavy and that's not good.

GM had to increase brake capacity when they started offering OEM 20s (maybe even larger) on SUVs.  A guy at work admitted he noticed longer braking distances when he switched to 20s from the OEM 16s.

While lug nuts are not very heavy to begin with, the additional rotating mass on front wheel drives has more effect on gas milage than rear wheel drive vehicles (even though it's an AWD).

Standard drive mode the Ridgeline is FWD unless they slip, then power goes to the rear.  It's neat coming out of corners hard on the gas; after minute front slippage it squats down & grips as the torque goes rearward. 

This is one of the reasons I never went with those huge rear tires on all the hot rods and muscle cars I've built in the past. I like to keep them low profile and use lightweight aluminum rims

My '04 Tahoe's OEM aluminum rims were 16s; I switched to OEM aluminum 17s.  The tire/wheel combinations were next to each other; the 1" larger diameter combo was noticeably & surprisingly heavier.  I could only imagine the difference w/ 20s; some fools go much larger than 20 now.

I dislike riding cruiser bikes but still like reading about them.  The cruiser guys like 240mm & wider rear tires now (sport bike tires are usually 180mm).  The marketing dopes constantly outsize each other.  Cruisers are cornering pigs by nature, as percieved style is their main reason to exist, but the wide tires further ruin cornering.  They of course resist turning, because the curvature, which assists in leaning, is too far from the centerline.  Even sport bike marketers succomb to this marketing pressure; some OEM tires are too wide & turn-in improves w/ a narrower width. 

[Daygloworange]

One marginal pound of rotating mass equals forty-pounds of added body weight
One marginal pound of revolving mass equals seventy-three pounds of added body weight
One marginal pound of recipricating mass equals eighty-eight pounds of added body weight

I'm not exactly sure this equates directly to Ribbon's original question. These might be more applicable to a race car than a passenger car. You have to be careful with these kind of comparisons. Where the "weight" is placed on a spinning object is important. Wheel lugs are close to the axis of the spinning wheel. The effects are going to be minimal. A pound close to the axis is not a big deal. The effect on ride at one pound is not going to be huge. When you factor what the average unsprung weight is on the average car per corner. One pound isn't going to do much, it's such a small percentage of the unsprung weight of a passenger car. It's all about ratios. You're aren't going to suddenly increase your gas mileage, get better braking, acceleration and ride quality from titanium lug nuts on a 3800 lb truck.

When you upsize the wheel, the mass of the wheel is further away from the axis. It's the effect of a lever. There is also the added mass of the casting to achieve the larger radii of the larger wheel. This added weight is multiplied as it spins due to centrifugal force. This does negatively affect braking and acceleration, and unsrung weight. Often though, the increased harshness in ride is more an effect of a lower sidewall height in the tire than the actual effects of the added unsprung weight.


Cheers

[Russell Dawkins]

Must go briefly OT to mention that when I first twigged to unsprung weight, thanks to an article in Road & Track in the '60s, I bought a car partly because they had gone to such extreme lengths to optimize this. That was the Rover 2000TC. Rover went so far as to mount the rear disc brakes inboard, next to the diff. The braking force was transmitted through two U-joints and a half shaft to the wheels which were, as a result, very light. In addition there was about 9 inches of suspension travel.

I used to win road races against cars with three times the horsepower by finding traction where they couldn't.

The ride was phenomenally comfortable, too.

[Folsom]

I would not try to tell you to have small wheels, just the lightest ones you can reasonably afford. You will notice the difference in accelerating and braking.

Increasing wheel size while decreasing wheel weight is good for running bigger brakes. This is what race cars do, they have the biggest lightest wheel so they can have the biggest most powerful multi-piston caliper.