Model 3 mods

[gearchruncher]

Yeah light wheels being a performance advantage due to inertia and unsprung weight is one of those true things that is often vastly overstated

Quick math:

4,000 lb car @ 70 MPH: 888,000 joules
1 lb @ 70 MPH, 17" diameter: 182 joules

Yeah, so each pound you take off is 730 joules at 70 MPH, out of 888,000. 0.09%.

GRM added 12 POUNDS per corner to a MIATA and changed lap times by 0.31 seconds. No magic expensive forged wheel is going to save you 12 lbs vs any other reasonable wheel.

 

[tm1v2]

I absolutely felt a difference and benefit from replacing the uber-heavy 20" Uberturbines with much lighter 18" forged wheels. Very very obvious. The power steering just felt better overall, the car felt more nimble in quick back-and-forth turns. This was with 100% stock suspension still (no longer the case). I honestly wasn't expecting that much improvement, I was downsizing just for protection from bad roads / potholes.

Now would I have felt most of that same benefit from decent flow-formed cast 18" wheels? Yeah I think so. I went forged for the extra strength, not because I was counting exact pounds. $1k for decent cast 18s is certainly better value than the $2k I spent on forged, no question. But FOR SURE much lighter wheels - whether cast or forged - can be felt through the steering wheel and improve how the car feels in the twisties. That's in large part because those Uberturbines are just ridiculously heavy, there's no other way to put it.

(No I couldn't feel any acceleration difference. Any possible acceleration improvement was too small for me to feel or care about. I don't really do max acceleration runs anyways.)

 

[jackmott]

I absolutely felt a difference and benefit from replacing the uber-heavy 20" Uberturbines with much lighter 18" forged wheels. Very very obvious. The power steering just felt better overall, the car felt more nimble in quick back-and-forth turns. This was with 100% stock suspension still (no longer the case). I honestly wasn't expecting that much improvement, I was downsizing just for protection from bad roads / potholes.

Now would I have felt most of that same benefit from decent flow-formed cast 18" wheels? Yeah I think so. I went forged for the extra strength, not because I was counting exact pounds. $1k for decent cast 18s is certainly better value than the $2k I spent on forged, no question. But FOR SURE much lighter wheels - whether cast or forged - can be felt through the steering wheel and improve how the car feels in the twisties. That's in large part because those Uberturbines are just ridiculously heavy, there's no other way to put it.

(No I couldn't feel any acceleration difference. Any possible acceleration improvement was too small for me to feel or care about. I don't really do max acceleration runs anyways.)

A confounding factor is you also changed tires when you changed wheels, tires have a massive impact on how a car feels. As well human perception is just terrible at these things, no matter how smart/expert we are. I did this same 20" uberturbine to 18" swap and didn't notice anything. But I am so skeptical of my own perceptions, so who knows maybe I just got too cynical =)

 

[tm1v2]

A confounding factor is you also changed tires when you changed wheels, tires have a massive impact on how a car feels. As well human perception is just terrible at these things, no matter how smart/expert we are. I did this same 20" uberturbine to 18" swap and didn't notice anything. But I am so skeptical of my own perceptions, so who knows maybe I just got too cynical =)

Yeah, to be fair even just changing inflation pressure can be felt and have similar effects. And I did play around with inflation levels on the new tires a bit. The tire shop started me off around 44-45psi cold which felt too high, I ended up back around 42psi cold, currently 42.5psi cold, set during mild daytime temps (so they do drop lower on actual cold nights and such).

I'm not claiming what I felt would actually translate to consistently faster lap times on a racetrack, or anywhere else. Just it felt nicer for tight twisties which is the majority of my fun driving these days. I could feel the difference in casual driving too but I wouldn't say it mattered at all in casual driving.