Lighter wheels for better acceleration

[Idaho2018GTPremium]

And in typical auto journalist fashion they completely miss most of the "why". MotorTrend is guilty of this too. The R model runs on 30 series tires and so therefore enjoys a roughly 4% gearing advantage over its non-R brother.

The biggest performance advantage for lighter wheels (and more specifically carbon fiber) is direction changes and carbon's superior resistance to deflection compared to aluminum in hard corners.

Is there a difference? Yes. Is it as much as people would like to believe? I don't think so. Maybe at the drag strip where every 0.01sec counts. We're not comparing 50lb wheels to 10lb wheels.

Overall handling and ride quality? Sure.

This is why I did a calc. - to see how much a lighter wheel package would theoretically improve acceleration rather than just estimate or guess. My stock '18 PP1 w/ MagneRide is more than adequate for me on twisty back roads, so I'm less interested in the handling gains, but realize they would be there and that is an added benefit. That said, gaining a tenth from 0-100 mph would be icing on the cake, and 14 hundredths in the 1/4 mile is not world changing, but it is quicker, and gives similar gains in e.t. to an aftermarket tune. If C&D had 14 hundreths their test for the '18 GT PP1 A10 would have yielded a 11.9X second car instead of a 12.1 second car.

One thing to keep in mind is the higher gears benefit more from the lighter wheels. That is because the energy required to rotate the wheels is the same, but the available torque at the rear wheels drops in higher gears, so therefore, a higher percent of the available torque is going to rotate the wheels. So, a 60-120 mph run would improve by about 0.09 seconds, vs a 0-60 run improvement of 0.05 sec.

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[2morrow]

Hey OP, nice calculations. I think that you'll be really happy with the FEEL of the car (steering input, change of direction, etc.) when moving to not just a lighter wheel but rotor(s) as well.

The aesthetics are a nice bonus too.

 

[Less Weight]

From my experience, lighter wheels have a significant impact on performance, wether it be acceleration, braking or handling.

I recently replaced my heavy ass PP1 wheels with a set of Apex EC-7 wheels and was quite pleased subjectively as well as objectively with the difference they made.

Here's my review of the wheels from the thread I made regarding them:

To say that these wheels have transformed the car would be an understatement. I've performed extensive weight loss measures on my GT but these wheels are far and beyond the most impactful and noticeable.

After getting the new 18x9.5 EC-7 wheels mounted onto new tires, I weighed each complete unit and compared them to the stock Performance Pack wheel and tire combo. The results are as follows:

- Rear (wheel/tire/tpms/and center cap): 49.1575 lbs. That's a net loss of 15.1425 lbs. per side so that's 30.285 lbs. off of the rear axle alone!
- Front (wheel/tire/tpms/ and center cap): 47.1375 lbs. That's a net loss of 13.4625 lbs. per side so that's 26.925 lbs. off of the front axle!

And if you're curious as to how accurate these weights are, they are completely accurate since they were weighed on $5000 weights and measures calibrated scales (which I calibrated myself). So these claims are verified.

For those looking for the biggest bang for the buck performance enhancement, don't hesitate to get yourself a set of these wheels; the gains are tangible. Instead of the tires crashing over road imperfection, thus upsetting vehicle control, these wheels, by virtue of their light-weight, simply soak up everything without any drama. I swear, it feels like I have an entirely new suspension setup even though my suspension is completely stock. There is so much more composure and control.

Oh, and as an added benefit, you know that simultaneous quiver, shutter, shimmy, circular bob that occurs when you hit highway expansion joints, railroad tracks, or any other road imperfections? Guess what? IT'S GONE! For the longest time I was buying into the consensus that the GT's suspension is underdamped and the spring rates too soft but after this change I'm realizing that instead they were overburdened by excessive weight. I'm not saying that the suspension is perfect; far from it. But many of it's shortcomings can be mitigated by cutting away approx. 30lbs. rear/27 lbs. front from the axles.

And how'd I forget about the wheel hop!? I'm not going to say it's completely gone but these wheels have made a HUGE difference. Wheel hop has been greatly reduced since the suspension has so much less weight to control.

Thanks again, Cory; great effin' product and service!

At the time of my review I hadn't performed any 0-60 tests but since then I have. The results are as followed:

- Stock PP1 wheels mounted to stock Pirelli 275 rears/255 fronts: The best 0-60 time I could muster was 4.8

- Apex EC-7 18 x 9.5 wheels all around. Tires are General G-Max RS 255/40 zr 18 up front and 275/40 zr 18 in the rear: The best 0-60 time I could muster with these thus far is 4.4.

Ambient temperatures between the different setups were very similar as were tire condition.

Now, there is a caveat here: When I performed my test with the OEM wheels and tires my car was stock. The tests done after mounting the new wheels and tires were accompanied by weight loss measures such as rear seat delete and about 20 other parts I stripped out of the car.

However, with that said, the most significant loss of weight was from the wheels.

 

[Idaho2018GTPremium]

From my experience, lighter wheels have a significant impact on performance, wether it be acceleration, braking or handling.

I recently replaced my heavy ass PP1 wheels with a set of Apex EC-7 wheels and was quite pleased subjectively as well as objectively with the difference they made.

Here's my review of the wheels from the thread I made regarding them:



At the time of my review I hadn't performed any 0-60 tests but since then I have. The results are as followed:

- Stock PP1 wheels mounted to stock Pirelli 275 rears/255 fronts: The best 0-60 time I could muster was 4.8

- Apex EC-7 18 x 9.5 wheels all around. Tires are General G-Max RS 255/40 zr 18 up front and 275/40 zr 18 in the rear: The best 0-60 time I could muster with these thus far is 4.4.

Ambient temperatures between the different setups were very similar as were tire condition.

Now, there is a caveat here: When I performed my test with the OEM wheels and tires my car was stock. The tests done after mounting the new wheels and tires were accompanied by weight loss measures such as rear seat delete and about 20 other parts I stripped out of the car.

However, with that said, the most significant loss of weight was from the wheels.

Interesting analysis - thanks for sharing. I don't think I could go from 19" to 18" from an aesthetics perspective. Saving that much weight in wheels would equate to just under a tenth of a second 0-60 mph (not accounting for the smaller dia. which equals even less rotational inertia). I noticed that you used the same width/profile, but on a 1" smaller wheel (19" stock vs 18" new wheels). So, some of the improved 0-60 time was also due to the gearing advantage of the smaller diameter tire (more torque at the rear wheel contact patches), in addition to the significant wheel/tire weight loss, and the other weight loss items, and likely a slightly better start.

I am this close to pulling the trigger on the 24 lbs SVE R350 wheels...

 

[Nagare]

I am this close to pulling the trigger on the 24 lbs SVE R350 wheels...

R357s are another 1.2lbs lighter per wheel, same price and options too.

 

[2morrow]

I am this close to pulling the trigger on the 24 lbs SVE R350 wheels...

Dooooeetttttttt!

 

[ZX3ST]

This is why I did a calc. - to see how much a lighter wheel package would theoretically improve acceleration rather than just estimate or guess. My stock '18 PP1 w/ MagneRide is more than adequate for me on twisty back roads, so I'm less interested in the handling gains, but realize they would be there and that is an added benefit. That said, gaining a tenth from 0-100 mph would be icing on the cake, and 14 hundredths in the 1/4 mile is not world changing, but it is quicker, and gives similar gains in e.t. to an aftermarket tune. If C&D had 14 hundreths their test for the '18 GT PP1 A10 would have yielded a 11.9X second car instead of a 12.1 second car.

One thing to keep in mind is the higher gears benefit more from the lighter wheels. That is because the energy required to rotate the wheels is the same, but the available torque at the rear wheels drops in higher gears, so therefore, a higher percent of the available torque is going to rotate the wheels. So, a 60-120 mph run would improve by about 0.09 seconds, vs a 0-60 run improvement of 0.05 sec.

And what assumptions are you making in that calculation? Solid discs of uniform distribution?

Unless you have very detailed dimensions of OEM vs any other aftermarket wheel and run extended calculations on it, it's still a guess.

Don't get me wrong, there are many upsides to aftermarket wheels. I just don't think weight should be the primary driving factor for a street car.

For what's it's worth for anecdotal evidence, by butt dyno noticed a huge improvement going to an aftermarket forged wheel. But I also changed from Pilot Supersports to Cup2 at the same time. I attribute most of the felt performance increase to the tires, not the wheels.

Those wheels you posted look great and you'd certainly be happy with them. Load them up with the same tires as you're running now and compare.

 

[Idaho2018GTPremium]

And what assumptions are you making in that calculation? Solid discs of uniform distribution?

Unless you have very detailed dimensions of OEM vs any other aftermarket wheel and run extended calculations on it, it's still a guess.

Don't get me wrong, there are many upsides to aftermarket wheels. I just don't think weight should be the primary driving factor for a street car.

For what's it's worth for anecdotal evidence, by butt dyno noticed a huge improvement going to an aftermarket forged wheel. But I also changed from Pilot Supersports to Cup2 at the same time. I attribute most of the felt performance increase to the tires, not the wheels.

Those wheels you posted look great and you'd certainly be happy with them. Load them up with the same tires as you're running now and compare.

I'd say it's more like an estimate; but no, I didn't do a rotational inertia analysis. My assumption was simple in that for a wheel, 1 lbs saved = 2 lbs unsprung weight saved. I didn't do a detailed take-off of the wheel differences. I then used F = ma, gear ratios, average engine torque, and time to velocity formula to compute the difference in acceleration. My calc. is setup to add other weight loss measures into it as well (i.e., lighter exhaust, rear seat delete, etc.).

I'm not looking for accuracy down to a gnat's ass. I wanted an estimate of what I could expect by simply replacing the wheels with lighter wheels. Turns out, for acceleration, it's similar to adding 10 hp, give or take.

That said, going from 33+ lbs per wheel to 24.4 lbs per wheel can't hurt, right?

 

[ZX3ST]

I'd say it's more like an estimate; but no, I didn't do a rotational inertia analysis. My assumption was simple in that for a wheel, 1 lbs saved = 2 lbs unsprung weight saved. I didn't do a detailed take-off of the wheel differences. I then used F = ma, gear ratios, average engine torque, and time to velocity formula to compute the difference in acceleration. My calc. is setup to add other weight loss measures into it as well (i.e., lighter exhaust, rear seat delete, etc.).

I'm not looking for accuracy down to a gnat's ass. I wanted an estimate of what I could expect by simply replacing the wheels with lighter wheels. Turns out, for acceleration, it's similar to adding 10 hp, give or take.

That said, going from 33+ lbs per wheel to 24.4 lbs per wheel can't hurt, right?

Certainly won't hurt.

I'm not suggesting accuracy to a gnat's ass, but ignoring real world difference vs theoretical is going to throw a really big wrench in your math. You'll need to figure some amount of fudge factor. Much of a wheel's weight is distributed near the barrel, and is a big reason why guys like to run smaller diameter wheels in racing where they can get away with it. (plus cost of tires is generally lower too)

Did you factor aero drag and rolling resistance into that calculation as well? I suspect those alone will be enough to throw off your calc by an order of magnitude.

I realize this is all academic, and semantics, but I still stand by my statement that tires will make the most difference.

At the end of the day, I'm just trying to be helpful, not argumentative. Realistic expectations.

 

[Idaho2018GTPremium]

Certainly won't hurt.

I'm not suggesting accuracy to a gnat's ass, but ignoring real world difference vs theoretical is going to throw a really big wrench in your math. You'll need to figure some amount of fudge factor. Much of a wheel's weight is distributed near the barrel, and is a big reason why guys like to run smaller diameter wheels in racing where they can get away with it. (plus cost of tires is generally lower too)

Did you factor aero drag and rolling resistance into that calculation as well? I suspect those alone will be enough to throw off your calc by an order of magnitude.

I realize this is all academic, and semantics, but I still stand by my statement that tires will make the most difference.

At the end of the day, I'm just trying to be helpful, not argumentative. Realistic expectations.

Ha, I did not factor drag into the equation. Talk about Gnat's ass. Most likely they are similar enough as to be negligible. As far as rolling resistance, the calc. assumes the same times, so no or very negligible differences.

I understand how smaller diameter wheels help, but that wasn't the point of the estimate. The point was to get an idea of the gains in acceleration that could reasonably be expected, and whether those gains would be worth it as I consider the wheels for those gains, handling improvements, braking improvements (albeit traction limited), and aesthetics.

 

[Idaho2018GTPremium]

Dooooeetttttttt!

I just bought 'em! Freaking stoked. Went with 19x10s all around. As much as I wanted the Bronze finish, I just don't like satin or matte finishes, so I went with the gloss black, because I know that will look awesome on Ingot silver. Also, I think bronze looks great with a lot of colors, but silver is probably not the best match, IMO.

Certainly won't hurt.

I'm not suggesting accuracy to a gnat's ass, but ignoring real world difference vs theoretical is going to throw a really big wrench in your math. You'll need to figure some amount of fudge factor. Much of a wheel's weight is distributed near the barrel, and is a big reason why guys like to run smaller diameter wheels in racing where they can get away with it. (plus cost of tires is generally lower too)

Did you factor aero drag and rolling resistance into that calculation as well? I suspect those alone will be enough to throw off your calc by an order of magnitude.

I realize this is all academic, and semantics, but I still stand by my statement that tires will make the most difference.

At the end of the day, I'm just trying to be helpful, not argumentative. Realistic expectations.

One shortcoming of my calc. is the fact that it doesn't account for the faster rotational speed as ground speed increases. So, my estimate is probably off even more at higher speeds. Which means, gains at higher speeds are likely higher than my calc. shows. That's probably why it is so noticeable for those that have updated their wheels to a lighter set.

 

[Idaho2018GTPremium]

Now I'm probably going to also buy a lightweight Steeda aluminum driveshaft if it fits on the 2018+ A10 GT. 19 lbs lighter than factory and because of the much higher rotational speed compared to the wheels (albeit smaller diameter), the driveshaft has a larger impact per pound saved than wheels when it comes to acceleration.

Does anyone here have any experience with these? How's drivability? Is there any vibration or harshness, or any other factor that would be a con to having a lightweight aluminum one piece driveshaft compared to the factory driveshaft?

EDIT: Nevermind. The Steeda driveshaft for the auto. is only 8 lbs lighter than factory. Cost benefit analysis says negative, sir! I'll keep looking...

 

[2morrow]

I just bought 'em! Freaking stoked. Went with 19x10s all around. As much as I wanted the Bronze finish, I just don't like satin or matte finishes, so I went with the gloss black, because I know that will look awesome on Ingot silver. Also, I think bronze looks great with a lot of colors, but silver is probably not the best match, IMO.

Congrats and thats gonna look great! FWIW, Silver is my fave color on many cars, especially the s550.

 

[GT5.0Fan]

We also have fuel economy difference for weight loss as well. Some say there are gains and some say there are losses on the highway at higher speeds.

 

[Flyhalf]

keep in mind that in most cases unless you are spending BIG money, saving weight with brake rotors is just removing material and compromising the structural integrity of the rotor. not worth the small weight savings

I respectully disagree
Usually a GOOD after market 2 poece rotor will increase the life of your brakes because the extra cooling you are providing.
Also will permit to the disc to expand better and freely due to the heat.
Most of the after market 2 piece rotors are slotted (DON'T BUY DRILLED ROTORS. THOSE ARE POSSIBLE TO CRACK AROUND THE HOLES)
the slots willmhelp to clean the excess pad deposit. Mantaining the rotor cleaner.
Main 2 companies I would recommend are
Girodisc or APR RACING ESSEX
girodisc around 1000$ for the 2
essex for 1500

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