Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com - View Single Post - Lighter Weight Wheels --- Worth It?

tournapart · 08-28-2009, 07:16 PM

Totally new here, just signed up, but I have read this 8 page thread and am in the same boat as the original poster. I have a Mazda RX8, which yes, its a sports car that gets horrible mileage, and for its mid price range is probably amongst the worst. That being said, I am an avid car enthusiast and am studying to be an engineer. To take it further, I did complete a vocational program at a community college for auto repair, and have been quite involved with rotary engines for years. I am interested in making my car a little more efficient. To filter the BS so to speak this is what I have taken from this specifically and a mix of what I have read in the past.

Talking strictly wheels

Lighter wheels will promote greatest fuel effciency in more urban/stop and go environments.

More aerodynamic wheels will promote greatest fuel efficiency in more highway/constant speed environments.

Now dipping into how much more efficient as you get more aerodynamic or lighter is debatable. I share the same sentiment as someone who posted earlier, not sure if its the original or not, as saying, I would get them anyways, the fact that they are more efficient is just a plus.

I wont sit here and say that my intentions are strictly efficiency, obviously if that were the case I wouldn't own a sports car. But it is a hybrid affair, fun/daily not gas/electric, and I think I can try to squeeze some more MPG's out and enjoy the car even more.

After reading this thread I was up in the air about upgrading my wheels once again. Stock, my rims were 23-24lbs each. When I discovered that one of the rear rims was slightly warped when I was getting some tires installed I went out and found a set of cheap rims to get me over. These turned out to be more like 26-27lbs each. The rims I am thinking (and now am definitely) of getting are 18.6lbs each (Enkei RPF1). I think there are many things to be gained having lighter rims, less wear and tear on wear components, such as brakes, tires, clutch, suspension, etc. Acceleration improvements will be the most noticeable and I think there is something to be said about being able to put less power out to get to accelerate as much as it did before the weight reduction (more of as a real world application versus a study of efficiency), everyone has different driving styles that make them feel comfortable when they drive their cars.

I am unclear on one thing. From my readings today, and of years past, there is always some heated and unproved debates of the equal ratio of unsprung to sprung weight. Some say 1:2, some say 1:3 I have read as high as 1:10. What are the exact variables that determine this ratio? and how could you apply these variable to any vehicle? I guess what I am getting at is, is there a fill in the blanks calculator that will tell me for my specific vehicle (curbweight, HP, etc) what my unsprung to sprung weight ration is? or is it infact a fixed ratio that is applied to all vehicles and everyone is just giving it they're best guess?

Thanks again to all who contributed to this thread, it has help me immensely and I hope to get to know some of you smart people out there.

08-28-2009, 07:16 PM	#75 (permalink)
tournapart EcoModding Lurker Join Date: Aug 2009 Location: El Sobrante, CA Posts: 2 RX8 - '04 Mazda RX8 Sport 90 day: 16.71 mpg (US) Thanks: 0 Thanked 0 Times in 0 Posts	Totally new here, just signed up, but I have read this 8 page thread and am in the same boat as the original poster. I have a Mazda RX8, which yes, its a sports car that gets horrible mileage, and for its mid price range is probably amongst the worst. That being said, I am an avid car enthusiast and am studying to be an engineer. To take it further, I did complete a vocational program at a community college for auto repair, and have been quite involved with rotary engines for years. I am interested in making my car a little more efficient. To filter the BS so to speak this is what I have taken from this specifically and a mix of what I have read in the past. Talking strictly wheels Lighter wheels will promote greatest fuel effciency in more urban/stop and go environments. More aerodynamic wheels will promote greatest fuel efficiency in more highway/constant speed environments. Now dipping into how much more efficient as you get more aerodynamic or lighter is debatable. I share the same sentiment as someone who posted earlier, not sure if its the original or not, as saying, I would get them anyways, the fact that they are more efficient is just a plus. I wont sit here and say that my intentions are strictly efficiency, obviously if that were the case I wouldn't own a sports car. But it is a hybrid affair, fun/daily not gas/electric, and I think I can try to squeeze some more MPG's out and enjoy the car even more. After reading this thread I was up in the air about upgrading my wheels once again. Stock, my rims were 23-24lbs each. When I discovered that one of the rear rims was slightly warped when I was getting some tires installed I went out and found a set of cheap rims to get me over. These turned out to be more like 26-27lbs each. The rims I am thinking (and now am definitely) of getting are 18.6lbs each (Enkei RPF1). I think there are many things to be gained having lighter rims, less wear and tear on wear components, such as brakes, tires, clutch, suspension, etc. Acceleration improvements will be the most noticeable and I think there is something to be said about being able to put less power out to get to accelerate as much as it did before the weight reduction (more of as a real world application versus a study of efficiency), everyone has different driving styles that make them feel comfortable when they drive their cars. I am unclear on one thing. From my readings today, and of years past, there is always some heated and unproved debates of the equal ratio of unsprung to sprung weight. Some say 1:2, some say 1:3 I have read as high as 1:10. What are the exact variables that determine this ratio? and how could you apply these variable to any vehicle? I guess what I am getting at is, is there a fill in the blanks calculator that will tell me for my specific vehicle (curbweight, HP, etc) what my unsprung to sprung weight ration is? or is it infact a fixed ratio that is applied to all vehicles and everyone is just giving it they're best guess? Thanks again to all who contributed to this thread, it has help me immensely and I hope to get to know some of you smart people out there.