So I'm considering some aftermarket wheels for my 2015 Fit. I want lighter wheels than the 16" OEMs and I want 7" width vs. the standard 6" width. I've read that lighter wheels can help improve MPGs, but wider contact patches can increase road friction and therefore decrease MPGs. My question: What is the impact or significance of weight vs. width on MPG?

Is there a linear relationship demonstrating that a reduction per 1.0 lbs (all things remain equal) yields a % increase?

Is there a detectable drop in MPG moving from 185 to 195 or 205 tires (all things remain equal)?

Will one cancel out the other?

Thanks!

 

I went from a the stock 195/55/16 to 205/50/16 and there isn't any noticeable MPG change and I track my fill-ups on a spreadsheet. I made a post about it here: General Altimax RT43 in 205/50/16

As far as wheel weight, it should theoretically get you better MPG since the engine doesn't have to work as hard to spin the wheels, but by how much I'm not sure. I'm thinking negligible. Acceleration/deceleration should be better though.

 

I think tire selection will make more difference than the wheel size. I recently put on a set of 16x7" Enkei RPF1 wheels, so fairly light, but dropped something over 2mpg. The reason is almost certainly the BF Goodrich Comp2 summer tires (205/50/16), which were sticky enough to save me from a lunatic in a minivan last week.

Guy changed lanes into me without looking or signalling, on a wet freeway. Had to swerve away hard enough to avoid him and then steer hard the other way to avoid the concrete wall rapidly approaching. Had I been on the previous Federal 657 Steels, I would probably have slid into the wall. Saved the extra fuel cost for the life of the tire by avoiding the crash, so I'm happy with it.

 

Lighter rims help as you're decreasing rotating mass. But if you're going to a wider tire, it's probably a wash.

Rather than going the lighter rim/wider tire route, I think you'd be better off with a low rolling resistance tire on your stock alloys. I had good MPG results with Michelin Hydroedge and later Michelin Defenders on my GD3 with the stock alloys.

 

Out of curiosity, why are you looking for wider wheels? Is your goal to get maximum lateral grip, by putting wider tires than the stock wheels will take? You're not going to increase traction (friction) and reduce fuel consumption (rolling resistance) at the same time. If economy is the goal, then extra width won't help.

 

your also forgetting the increased friction if you’re going from say a 480TW to say a 280TW. I assume you will be based wanting to go to a wider wheel? You’re also not taking tire weight as part of the equation.

Anyway i I put my OEM 195 wide tire tires on a 7” wide wheel. I didn’t weigh either the stock vs the aftermarket that I bought used. No difference in gas mileage. I do have a set of TR wheels that are also 7” wide and are lighter than OEM. I have a set of 205/50/16 RE-71R that I use for autocross. They are 200TW tires. I loose about 3mpg in fuel economy with them on. I would suspect it’s due to the TW rating, not the 1 centemetet increases in width or the increase in wheel diameter?

 

Rob H- your experience seems to match mine.

 

Good question. In short, I want my cake and eat it too. I'm very satisfied with the current mileage I get with the stock wheels, tires (Khumho P185/55/R16) - they look like standard all-season tires so nothing performance related.

Figured wider tires / wheels would give more lateral grip for spirited driving (not tracking this car). At the same time, I want to retain my gas mileage. Any gains would be great (but not expected); any losses I hope would be negligible.

I'm new to this (never "tricked out" my car before) so I'm trying to take a balanced, informed approach. There are many variables (tires, speed rating, width, weight, rotational force, etc.) that I want to account for before I take any big leaps in mods and money.

 

well in order to eat the cake youll need to pay to play. wats ur budget?

if only like a grand just get sticker tires on your stockers and save the rest for your next car that will perform out of the box.

 

If you're not changing tires the performance increase is going to be so small you're not even going to even notice with your "spirited" driving on public roads

Tires are the single biggest performance improvement in regard to handling. You're not going to make a silk purse out of the sows ear of tires that you have. Yet tires are often the most neglected. People rather brag about buying coil overs, sway bars, end links or something that's going to last instead of tires that are a consumable item.


You have no desire to track your car? That's fine many people don't. By wanting to do "spirited" driving you're implying that you think you're a better driver or as Yogi bear would say better than the average? Competing in autocross puts it in black and white exactly how good or how bad you are compared to a group of people who also think they are better than the average driver. Most importantly it will teach you car control and weight management. Maybe you're a natural, maybe not? FYI: if you're pushing the tires that much to their limit on the street you're endangering someones life. Yours or the soccer mom in the minivan full of kids that didn't give her consent for you to endanger it. Most amateur motorsports require signing a waiver. Basically saying you might get hurt in the closed course competition by something you do or your competitor does.

My advice would be keep the setup that you have on the car and drive it like an adult on the street. Buy another set of wheels and more performance oriented tires and do a track day or autocross. About the worst that will happen in autocross is that you will scuff up the front bumper from some cones and have your ego bruised by being beat by some 17 year old girl in a Miata?

 

ok i saw yogi bear

 

I don't believe you need to go to the track to justify sticky tires. I don't believe spirited driving on the street has to be at 10/10ths, either. You can enjoy a twisty road (with enough visibility to slow for oncoming traffic) or a curved freeway onramp and stay within the safe margin of remaining traction, if not always within the speed limit.

Changing tires doesn't just increase your safety limit, it can also have a significant effect on the feel of the car. And even when driving in a calm and sedate manner, having that much extra traction to avoid the kind of maniac driver who thinks 10/10ths in traffic is reasonable, or worse, a teenager on the phone, can save you from a trip to the body shop or the hospital.

OP, my advice is to start reading tire comparison tests on Tire Rack, or wherever else you can find them. Tire Rack even lists comparative mileage within individual tests, but unfortunately not for their entire selection as a library. Figure out what works best for the driving conditions where you live. If one tire in a test has a dramatic improvement in fuel economy, maybe that's the one for you.

https://www.tirerack.com/tires/tests...y.jsp?ttid=222

 

you right, you dont. i run sticky tires on my hobby cars cause race car!