I do mostly highway driving and am curious if I can improve me Miles per gallon if I put on slightly oversized (larger diameter) tires?
Thanks!
Nope. Raising the car usually hurts. If you had really wide tires and switched to thin ones, maybe. Your gas mileage readings will seem like you are getting less MPG too, even if it stays the same because your speedometer will register less miles.
It would compromise your alignment and possibly safety. It’s not worth it even if it does increase your mileage by some infinitesimal amount. The best ways to improve mileage are to keep up on maintenance, keep your tires inflated and slow down, thats it.
No. Larger tires won’t improve anything, gas mileage, handling, and if too large may interfere with the frame or body of the car when fully turned.
There are differences in the “rolling resistance” of tires. Michelin is claiming “higher gas mileage” for some of their tires. Is the claim valid? Perhaps. For comparison shopping go to tire webs and check them out, ie tirerack.com
tire diameter is merely an extension of the overall gear ratios, and incorrect sizes can affect many things, including providing incorrect info to odometer, speedo, true mpg, make you likelier to get a speeding ticket, affect handling, etc. The aspect ratio of the tire, say a 55 vs. 60 will affect speedo by 5% approx, Best to stay within recommended range and look at rolling resistance, inflation, driving habits, etc. Narrower tires tend to get better mileage and remember the tire was selected for weight carrying ability, heat and traction, etc. but just putting a bigger dia. tire on is no guarantee of better mileage.
It depends on the car. A lot of performance oriented cars with manual transmissions are geared not for fuel economy but to satisfy owners who don’t want to downshift for passing power.
Most automatic transmission modern cars have an overdrive high gear that is optimum.
Many motorcycles are almost absurdly undergeared, permanently in a passing gear to satisfy a market that wants “torque”. I regeard a Yamaha SR500 by replacing the stock 16 tooth countershaft sprocket with a 17 tooth sprocket and that resulted in a significant increase in gas mileage plus the bike was no longer such a buzz bomb on the highway. Since this bike’s speedometer was driven by the front wheel, there was no speedometer error.
I will take a different position here and say “It depends”. It depends on how far off you are from your car’s current “sweet spot” for your engine power, rpms, weight, normal driving conditions, etc. It also depends on how your car’s control module is programmed to handle inputs that are just outside of the expected inputs.
After compensating for the speedometer/odometer being off, I have seen cases where gas mileage did improve slightly.
However, as the other notes have indicated, you need to be careful about how it impacts the handling. You are changing the handling geometry.
Wheel-well clearance is also a concern. How will you determine that your larger tire will not rub on the wheel-well when your wheel is turned and you hit a dip/pothole that causes your suspension to compress to its full range? That’s not the time you want to learn that you’ve just worn a hole through your sidewall.
My vote would be to stick with the size(s) specified by the manufacturer.
“It depends”. It depends on how far off you are from your car’s current “sweet spot” for your engine power, rpms, weight, normal driving conditions, etc.
I will add a little to that. There are a number of sweet spots and they are moving targets.
You will have one sweet spot for best mileage and likely a different one for power and maybe a third for max engine life. Each of those will vary depending on the temperature, driving conditions and driving style.
All things considered, there is little to be gained or lost by changing tyre size. Extreme changes would usually be detrimental to all the sweet spots.
Thanks for all of the insights! It seems that there is no gain, yet many potential problems.
Not to mention that steering gets more difficult.