I currently have 17's that weigh in at about 26lbs. If i replaced them with lightweight wheels that are 18lbs./each, what positive things can i expect from it?

Mileage? Smoother ride? Better braking?

And is a lightweight 17" always going to be better than 18's of similar weight?

Thanks!

 

All of the above.

I noticed an increase in MPG. 12-15% going from stock 24lbs wheels(17x7, 225-50), to 14.3lbs wheels(17x8, 245-45). feels lighter/quicker. Hopefully I'll get on the humblemaker soon to see what is actually going on in that department.

 

Thanks for the response! This is good to know.

Would you go as far as saying that lighter wheels will also make the suspension work better, especially on rougher roads? or will i just be feeling more bumps since the shock can easily move the wheels now?

 

I can't give you numbers but my car feels quicker when I go from my stockers to my Kosei Penta's (16.1 lbs). I thought it was in my head until my wife asked why the car felt slower the first time she drove it after putting the stockers back on for winter.

 

You'll also feel the difference in your braking performance too. I did when I went from my Lowenharts LH5s (28lbs) to Superleggeras (19lbs)... Now i'm back to the Lowenharts but luckily I have the AP's now...

 

Thank you, all, for the response! Just what i had hoped for.

Now to figure out if i should go for lightweight 17's or 18's (Same weight, different styles).

 

LW 17's, even if they're same weight as the 18's, will benefit you more due to their smaller rotating mass.

 

Is this because tire is considered as weight that is away from the axis of rotation?

IMO, if set up is the same overall height it should not matter much and will depend heavily on wheels construction...

 

Has more mass to rotate further away from the hub. Smaller diameter is better.

 

Same weight rims and tires, 17" vs 18", difference should be negligable... However, 16" vs 18" would make some diff...

 

Agreed that it's negligible. Albeit negligible, the 17 is still more efficient.

 

and what are these lighterweight tires.

 

Not lightweight by trade, but Tirerack has weights on them. I got the lightest on there 23.xx lbs. + my wheels = 14.3 lbs, total weight, 37.5lbs

 

WOW! I'm at 18 lbs for rims and 26 lbs for tires = 44 lbs and thought I was doing good

 

i cut all the tread off my tires to save weight

 

Just threw my wheel/tire combo on the scale...38.5 lbs.

 

8 lbs/wheel is HUGE.

The only note of caution I would give is to be careful picking tires. All else equal, a lighter tire has less robust construction. That means a weaker sidewall, which means you have to make up for it with more tire pressure, which means the tire turns into a basketball on rough roads, which means your suspension articulation argument is in the crapper. It's hard to make a tire that is well built AND light, so try to look more on the high end.

But yes, 8 lbs per corner is a really really big difference. The car will accelerate, brake, handle, ride, and track on rough surfaces noticeably better.

 

Thank you all, again, for your input! It's been really helpful.

On the mention of tires, i was going for the Proxes 4. It's served me well so far and the sidewall doesn't feel terribly soft but i'll put some more research into this area.

 

Some sizes of the Proxes 4s have terrible sidewalls -- my old Proxes 4s in 225/50/16 were V-rated and sucked in that department. But since you have 17" rims, the sizes you'd be looking at for the Proxes 4 are all W-rated and should be fine (no one ever complained about the sidewall of a 235/45/17). If the tires you have now have good enough sidewalls and you're keeping the same size and model, I wouldn't worry about it.

 

Why? Is the tire significantly more dense than the rim?

As per Igzy's comment above, if the OVERALL diameter is the same, the only difference between rotating a 16" rim versus an 18" rim is the 2" where there would be "tire" instead of "rim". Unless the weight per unit of volume between the two is VASTLY different, I don't see how this could amount to anything more than a very negligible difference.

I know this theory has been accepted for a long time on the ORG but I have never understood it and this seems to be as good a place as any to discuss it.

 

If you look at a 16" and an 18" wheel of the same width, the heaviest part of the wheel is where it meets the tire. That's because there's so much more metal there than in any other part of most lightweight wheels (think hub vs spokes here). Now think about the 18 and what its hub would be occupying on the corresponding 16" wheel/tire assembly. It's mostly air volume on the 16's tire with a bit of sidewall, but it's replaced by all that dense metal in the hub of the 18. Accelerating something farther away from the axle takes more effort than if it was closer. So from that theory, the 18 might hold its momentum better, but it will take more effort to get it up to speed.

 

Isn't the unsprung weight factor equivalent to 8.

An 8 pound reduction per wheel would equate to a 256 pound reduction in curb weight.

No wonder the car feels faster.

 

I think you mean rotating mass, yes?

8 lbs is a VERY approximate number and assumes all else is equal (wheel and tire sizes, etc.), but yes, that works fairly well.

 

Good explanation, thank you.