FastWgn

I thought our stock 10 spoke wheels were around 32 lbs each?

I.T. Guy

Yes

From this post here https://mbworld.org/forums/w212-amg/...ml#post7803866

E63 alloys
Front Wheels: 9Jx19 ET37 (p/n A2124015002) - 31.95lbs
Rear Wheels: 9.5Jx19 ET52 (p/n A2124015102) - 32.15lbs

I.T. Guy

And https://mbworld.org/forums/w212-amg/...ml#post7805715
E63 Forged
Front 9Jx19 ET3 A2124010800 24 lbs
Rear 9.5Jx19 ET52 A2124010900 26 lbs

So if aftermarket is 21 lbs you are only saving 3lbs over forged OEM. At such small weight savings it's just for looks at that point if you already have forged. Or go forged "Magnesium" @ 16lbs each

ThreeSix

i've had zero vibrations with the spacers and have gotten the car up past 120 plenty of times

The spacers were nothing special...these are the ones:

thesaintusa

But for those with the 10 spoke (32 lb wheels), dropping down to 21 lbs, is 10 lbs per corner.

You will definitely notice a 10 lb drop in wheel weight.

FastWgn

Absolutely - after some reading and talking, it seems like there is some convergence around a factor of ~8 in the "acceleration effect" of rotational mass. So, a 10 lbs weight reduction is equivalent to ~80 lbs of vehicle weight - in an acceleration scenario. So, loosing 10 ls per corner is around 4*80 or 320 lbs "lighter" than stock.
Yes, lots of variables in there - how the new wheel is constructed, assuming identical tires, no grip limitations etc, etc.

But the other value is that your unsprung weight in general is 10 lbs lighter, maker for better wheel control during suspension movements, so you get smoother absorption of bumps etc. Lastly - theoretically you get a sharper (read faster) steering response since you have less centrifugal force, but I think this is largely placebo after the power steering has done it's job.

thesaintusa

I can definitely vouch for the car being faster and feeling faster with lighter wheels.

My 93 RX-7 has 16 lb OEM wheels, and I went from those to 24 lb aftermarket wheels and regretted how it felt. Went to 17lbs TE-37s and was happy again (not the wallet though). Currently back on the OEM wheels and love how it drives, but not the look. New tires for the Volks are in the future after a new turbo setup.

Those old enough to remember the Gtech Pro may laugh, but with the same brand tires lost over 0.5 sec in the 1/4 mile consistently, and gained it back with the OEM wheels and the TE-37s. Suspect that a Dragy would show similar gains/losses with lighter wheels. As mentioned above, 8-10 lbs per corner will translate into real gains in the real world.

PeterUbers

Would you see a 0.5 second gain in the 1/4 on a heavy 4700lb e63, compared to a svelt 2500lb rx-7? Not criticizing just asking. I had a gtech as it was the first decent metric accelerometer to do home testing -- was great mostly to see the delta before and after mods...

this guy had similar results to you:
https://medium.com/@almirx101/lightw...n-b30c4b6189fe

FastWgn

@PeterUbers I think that is the point - or at least mine. Clearly you are not going to see the same absolute time results on a 4,700 lbs car as a 2,500 or even 1,200 lbs Caterham. The percentage improvement clearly goes down.
BUT, compared to removing 320 lbs of interior or go for light weight batteries etc to get increased acceleration performance, this is the way to go. Makes sense? We may be saying the same thing.

PeterUbers

definitely makes sense - now consider this - how much more of a tune would accomplish what 320lb weight loss would accomplish on a 4700lb car? Considering cost of wheels vs tune, safety, engine longevity, and strength of wheels and cost of retaining wheel aesthetics, cost of repairing a lighter wheel etc...

What's a set of equally strong lightweight (to OEM forged wheels) rims cost?

thesaintusa

@PeterUbers The gain may be 'relatively' less (4500 lb car versus 3000 lb car), but doesn't change the fact that it would be similar to dropping several hundred pounds from the interior.

I wish the RX-7 was 2700 lbs. I was under 3000 lbs with full interior / gas and myself.

@FastWgn

Bottomline, that bang for the buck a tune will yield better results, but in the quest for gains at the 1/4 mile, adding a set of light wheels can get people from low 11s down to 10.xx times, and those running high tens a set of uber light wheels could get you closer to mid 10s.

It all adds up. But for me, I definitely like how a set of lighter wheels makes the car 'feel'. I noticed this most when I slapped a set of r-cmpd tires on to a set of bloated aftermarket wheels. The combination of a TON of more grip and heavy wheels made the car feel terrible. Swapping the r-cmpds on back to OEM rims made up for the feel of the increased grip.

@PeterUbers I would expect that you would be spending $4-5k+ for a set of forged light wheels. My volks were used and cost me less than $2500. New would be closer to $4500. For a heavy car with a ton of power I would definitely buy something not just light but strong. FWIW, had some pretty hard pothole hits with the Volks, but they have always stayed straight and true.

FastWgn

Ah - I was not talking about either / or (tune or wheels).
I was thinking about two other scenarios:
1) People buy "big diameter, cool looking wheels" thinking they will get better performance. Fail.
2) Other spend many thousand installing light weight batteries, remove stock seats, etc all in the name of weight loss. Lighter wheels is an easier and cheaper path.

Tune (ECU and TCU) is a separate axis for me.

JimFE

Howdy:

At the risk of partially hijacking this thread, is there any opinion on here about the sturdiness/durability/resistance to fracture and bending of any of these aftermarket wheels? My car is still running the OEM black 10-spoke wheels and three have had to be replaced due to cracks. So I wouldn’t mind losing a bit of unsprung weight from the 32lb wheels, but definitely want something that is going to be resistant to damage. Those Volks a few posts above look really nice, are they durable?

thesaintusa

Volks will be durable on the track/road. You definitely have to pay to play, and you get your moneys worth with Volks. Love the look of the TE37

1. Cheap
2. Strong
3. Light

You can only get 2 of 3 when buying wheels.

Completely agree that you should stick with a wheel manufacturer that has a track record of use in the racing realm. Definitely do not want to go down the Rota route and crack a wheel and wreck your car.

You replaced 3 OEM 10 spoke wheels? Did you hit any pot holes? I have nailed some pot holes that I was convinced would result in a trashed tire/wheel, but my OEM wheels are still true (although I did lose a tire to a particularly large pot hole where I cut the wheel at the BEAD but the wheel was intact).

You will be very happy with Volk, Advans, BBS, OZ racing (but I have bent 2 OZ Ultraleggera wheels (suspect other models will be stronger) hitting pot holes (which I have never done with Volks, Advans or BBS).

JimFE

Hi:

I don’t recall hitting anything that would have cracked a wheel, though I’ve only had the car for a little less than a year. I replaced two of the wheels, the previous owner provided receipts for a third. Interestingly, they haven’t gotten out of balance, the symptom was they stopped holding air, and when removed from the car had cracks on the inside rim about 1” long. I haven’t seen a lot on the forums about these wheels being weak, and they sure have a lot of meat.

Thanks for the response. Def want strong, will give a little lightness for a little lower cost. Do want to stay with 19s, since I have a relatively new set of Pilot Sport 4S on the car, and I like the look of black.