Wheel & Tire Weight & Suspension Stress Question

[fherdeg]

Hi everyone,

I had a couple of wheel/tire/suspension stress questions that after conducting some research, I thought I would ask here.

I recently purchased my '93 500e and it has 18" x 8" AMG Aero 2 wheels originally intended for the W140. It has 20mm spacers up front and 25mm spacers in the rear. I like the look but based on some of my research on the board, I wondered if the spacers, wheels and tires are putting undue stress on the suspension? And if so, maybe I should do something about it.

If that is the case, I have the original wheels and I thought that I might put them back on to reduce the unsprung weight. I also love the 17" x 8" AMG Aero 1 wheels and considered looking for a set of these as well. But after doing some research on the weight this is what I found which is not what I expected:

1) An 18"x8" AMG Aero II Monoblock wheel (on my car) with a 235/40/18 tire mounted weighs ~52.0 lbs;
2) A 17" x 8" AMG Aero I wheel likely weighs between 21 and 25 lbs. A 235/40/18 tire weighs ~23 lbs for a total weight of ~44 - 48 lbs. lbs;
3) The 16" x 8" 500e OEM wheels weigh ~23 pounds and a 225/55R16 wire weighs ~24 lbs for a combined weight of ~47 lbs.

So my questions, after all of this noodling around, are:

1) should I be concerned about any additional stress put on my suspension with the Aero II wheels and spacers on my car, and

2) do the combined wheel and tire weights listed above sound accurate?

I was surprised that there wasn't more of a weight difference between 16"x8", 17"x8" and 18"x8" wheels and tires. I had expected the weights to go up with the wheel diameter which is probably naive as different materials and construction types would affect wheel weight. I'd like to get the lowest unspring weight wiht the best looking wheels which I realize is toitally subjective!

I am pretty sure I can detect the additional weight from my 18"x8" set up, even though they are the only wheels and tires I have ever experienced on the car.

Thanks in advance!

 

[gerryvz]

I believe spacers are never a good idea, although many many people here have run them over the years. I have never heard a catastrophic story with spacers (even large ones), but in my opinion it puts (geometrically) stress on things that the car wasn't really designed to take.

It is ALWAYS better to get wheels with an offset that doesn't require spacers, if at all possible. If you MUST run spacers, I would go 10mm or less. 20mm+ is really pushing it.

 

[gsxr]

1a) Don't worry about suspension stress / load. It won't make much difference without extreme offsets or extreme weight.

1b) Spacers will cause issues if they are not hubcentric, which is critical for any Mercedes application. Proper spacers are probably fine for street use but I'd be nervous about using them on a road course at high speeds without additional research and proper bolts. Gerry is correct, it's ALWAYS better to get wheels with an offset that doesn't require spacers.

1c) Wheels designed for M14 lug bolts, like your Aeros designed for the 140 chassis, must be used with bolts that have an R14 radius ball seat. Using an M12 bolt with R14 seat is dangerous. Be very careful with this when selecting bolts for your wheels.


2a) The weights you listed above are pretty close. Stock 500E wheels are right at 23-24 lbs each, with tires about 45-48 lbs (varies by tire brand). The 17x8 Aeros will be 24-25 lbs (NOT 21 lbs), and around 50 lbs with tires. The 18x8 Aeros are likely 25-28 lbs bare and 52-55 lbs with tires.

2b) Wheel weight doesn't increase proportionally with diameter, but in general larger diameter + wider will almost always weigh more, for a given style / construction (cast vs forged, etc). As an extreme example, I have some Brabus 17x8 that are 29 lbs each (!!), while a much larger 18x9.5 RENNtech Monolite weighed in at a feathery 21.4 lbs (these were weighed on a refrigerant scale accurate within a tenth or two).


Note that worn tires (near the wear bars) will be 3-4 lbs lighter vs new tires.

Any 17-18" wheel/tire combination that is <50 lbs total is darn good. Heaviest I've seen are >58 lbs.

 

[fherdeg]

Thanks a lot for the feedback, that's helpful.

The wheels are mounted with the R14 ball seat bolts so I should be safe there, thankfully.

It sounds like my 20mm and 25mm spacer setup is not ideal, and the wheel/tire setup sounds is the heaviest option so I will probably make a change. Now I just have to figure out if I want to find a set of 17" x 8" AMG Aero I's or refinish the stock wheels. Very different of course. I love the understated nature of the OEM wheels, but those Aeros are so very attractive. Decisions, decisions....

Thanks again!