3.7 pound difference per wheel. Noticable difference?

Techmonkey said:

Just a quick question regarding wheel weights. On a thread on another forum, I was comparing the TRM C1Ms ($99 for a 15x7 13.6 pound wheel) to Enkei RP-F1s ($199 for a 15x7 9.9 pound wheel). My statement had been that that the small difference in wheel weight would not make a noticeable difference to anyone but the most competitive drivers. I was told that is somewhat incorrect and the four pounds would make a difference in ride quality and traction.

So I ask the gurus of performance! Daily driver, autoX car, even HPDE; would there be any type of noticeable difference in ride or traction based on a 3.7 pound difference per wheel? If so, is it the type of thing the average Joe or weekend enthusiast would really notice?

Mark

Edit: Sorry, forgot to mention this is on an NB Miata. I know the car in question is an important part of the equation.

Hello all, 

I just wanted to piggy back on this as I have a similar question. I'm wondering if switching from my stock wheels around 28lbs to wheels that are 17.5lbs is too drastic of a change? I know others that have made the change but is it healthy for the car? Also I'm assuming this would make quite a noticeable difference since it's about a 44lb unsprung weight change. 

In reply to Steelerspro :

Too drastic? You pretty much can't have "too light" of a wheel. As long as it's structurally up to the job, it's a better thing. 

In reply to _ :

Thanks, I just wasn't sure seeing as most people I see are like a 3-5lbs change and mine would be about 11lbs a wheel. 

In reply to Steelerspro :

that's fantastic weight savings. What were your previous wheels? (Brand, and size)

In reply to _ :

18"Austin's switching to 18" OZ Alleggerita HLT's so I guess it's closer to 8lbs my mistake 

I just dropped 15 lbs per corner, for a total of 60 lbs off of my wheels and tires and the difference is noticeable.  The car accelerates with a little less effort, particularly at low engine speeds while off boost.  Initial turn-in is lighter and my muscle memory has had to adapt as I've found myself turning the steering wheel with too much effort.  I do have to question the "1 lb of rotating mass = 10 lbs of static mass" thing though, because my car definitely does not feel like it's dropped 600 lbs, it's more subtle than that.

Ride quality is...  interesting.  The ride feels more "chatty", as in I can feel a lot more small bumps in the road, but the harshness of larger bumps has definitely been reduced.

I can't speak to how the car feels at "full send" just yet as I'm still breaking in the new tires and I have a mechanical issue to deal with before I go hard on the engine.  I'm looking forward to seeing the difference the next time I get up to the mountains.  I'm also looking forward to seeing how they perform on Road Atlanta in a few weeks.

In reply to MrFancypants :

I haven't factored in the tire weight yet but 15lbs that's crazy awesome! 

Here's an article from a cool magazine which sometimes conducts tests to answer questions like this: https://grassrootsmotorsports.com/articles/are-lighter-wheels-really-better/

Snrub said:

Here's an article from a cool magazine which sometimes conducts tests to answer questions like this: https://grassrootsmotorsports.com/articles/are-lighter-wheels-really-better/

He's right. 90% of your questions have been answered by the staff of GRM. 

MrFancypants said:

Ride quality is...  interesting.  The ride feels more "chatty", as in I can feel a lot more small bumps in the road, but the harshness of larger bumps has definitely been reduced.

Seems reasonable to me. Small bumps encountered at speed primarily cause 'high-speed' motion of the unsprung mass. By significantly reducing unsprung weigh, the same damping force now has a greater effect.

Steelerspro said:

In reply to MrFancypants :

I haven't factored in the tire weight yet but 15lbs that's crazy awesome! 

Yeah, Volkswagen and their crazy heavy wheels, right?  15 lbs for me is both with the wheel and tire.  13 lbs with the wheel, and a surprise 2 lbs from the tire even though it's a 17 and not an 18.  Please post again when you get the OZs on your car, I'm curious to hear what you think.

Driven5 said:

MrFancypants said:

Ride quality is...  interesting.  The ride feels more "chatty", as in I can feel a lot more small bumps in the road, but the harshness of larger bumps has definitely been reduced.

Seems reasonable to me. Small bumps encountered at speed primarily cause 'high-speed' motion of the unsprung mass. By significantly reducing unsprung weigh, the same damping force now has a greater effect.

Certainly that, and something else I've come across while reading up on the topic is the idea that a heavier wheel tends to force the tire to conform around small road surface irregularities and not transfer that energy to the chassis through the damper/spring.  I'm not an engineer so I can't say how true this is, but if it is true it would make sense for Volkswagen engineers to choose such a heavy wheel to give a smooth and refined ride as the stock suspension has enough bump travel to soak up big hits with so much unsprung weight.

Huge fan of lightness.  You can really feel it in the brake pedal as well as the gas.

In reply to MrFancypants :

Yes, that seems plausible as well.

mad_machine said:

for the rest of us.. lighter is better. We argue the benefits of a solid axle over IRS.. but lighter rims (and tyres) can make just as big a difference.

The only benefits are simplicity and minor weight reduction (which is worse since you're changing the weight distrubtion to be more front-heavy). The solid axle in commuter cars only exists because it's cheaper to make.

If calculating weight reduction as a percentage for acceleration/deceleration sake, you need to factor in the tire, brake rotor, hub and driveline inertia too. The tire weight will have the biggest effect, as it's, well, bigger and the distance from the axis of rotation where the weight lies is important for inertia.

If calculating percentages for ride and handling, you'd need to consider all that (minus driveline), plus the upright and part of the control arms, sway bar, spring and shock weights and half shafts too, since part of them all move.

If you think about it in those terms, the difference seems much smaller, not that less weight doesn't have benefits. With wheels it's also important to consider stiffness, since if the wheel deflects more under load, you lose camber and therefore grip, or you need to add more static camber and lose straight line grip. This can make a heavier wheel faster overall.