Small tires compared to big tires. Stock 15" wheels with smaller than stock (to lazy to get actuall sizes) tires would take more spin to cover the same distance that a bigger tire would but holds less air and is overall less rubber, thus is lighter, but a bigger tire covers more ground in a single revolution, but holds more air and is made of more rubber, thus is heavier, right. so what would be the better performer or would be the best on gas. My reason for the question is my uncle of about 55 years of age puts bigger tires on everything he owns to save gas, but i don't quite see the logic in this. can someone help me out?
nissandude83
I think his logic is that the engine will be turning fewer RPMs at the same speed...therefore burning less gas while he drives at a constant speed. Cons I can think of would be that it takes more effort on the engine's part to get it moving, and acceleration would be slower.
On the other hand, your car could accelerate more easily with smaller tires, but the engine would turn higher RPMs to go the same speed because the tires have to make more revolutions to go the same distance, like you said. I think that on the highway, you'd get worse mileage, but in the city it might be a little better because the engine won't have to work as hard to get the car moving.
That's how I understand it at leas...just my $.02 after tax.
On the other hand, your car could accelerate more easily with smaller tires, but the engine would turn higher RPMs to go the same speed because the tires have to make more revolutions to go the same distance, like you said. I think that on the highway, you'd get worse mileage, but in the city it might be a little better because the engine won't have to work as hard to get the car moving.
That's how I understand it at leas...just my $.02 after tax.
That's right. Changing your tire diameter effectively changes the gearing of the vehicle. Smaller tires gears the entire drivetrain "lower" and will improve your acceleration but will generally raise the engine RPM at the same speed (assuming same transmission gear, of course), causing a drop in gas mileage but also an increase in engine wear.
With larger tires, the car won't pull as well, but the engine will rev lower at the same speed, hopefully improving your gas mileage. IIRC Someone made a point earlier that the Vulcan and Duratec final drive are different such that the Duratec actually gets about the same highway fuel mileage because the Vulcan has to turn higher RPMs at highway speeds than the Duratec.
A couple things to remember with bigger tires:
1. Although you may actually improve your mileage, your speedometer and odometer are not going to reflect this. The speedo will read lower and the odom will roll slower because you are turning the tires fewer times per unit distance. So when you calculate your gas mileage, it may not improve, even though you will have traveled more miles on the same volume of fuel.
2. In relation to that, you can figure out the percentage circumference increase of your big tires over the stock tires, assuming you can do the math. The speedometer reading times that percentage is how much faster than the speedometer says that you are actually going. Likewise, the odometer reading times that percentage is how many more miles you've traveled than the odometer says since you put the new tires on.
3. Keep in mind that your actual speed will be a few percent higher than the speedometer says. So if you were unhappy with your previous gas mileage at 55mph, adding a 5% larger tire and then drive where the speedometer still says 55mph, you will actually be going almost 58mph, and it's going to hit you with 10% more drag. You will have to be more careful if you like to abuse the speed limit, too.
With larger tires, the car won't pull as well, but the engine will rev lower at the same speed, hopefully improving your gas mileage. IIRC Someone made a point earlier that the Vulcan and Duratec final drive are different such that the Duratec actually gets about the same highway fuel mileage because the Vulcan has to turn higher RPMs at highway speeds than the Duratec.
A couple things to remember with bigger tires:
1. Although you may actually improve your mileage, your speedometer and odometer are not going to reflect this. The speedo will read lower and the odom will roll slower because you are turning the tires fewer times per unit distance. So when you calculate your gas mileage, it may not improve, even though you will have traveled more miles on the same volume of fuel.
2. In relation to that, you can figure out the percentage circumference increase of your big tires over the stock tires, assuming you can do the math. The speedometer reading times that percentage is how much faster than the speedometer says that you are actually going. Likewise, the odometer reading times that percentage is how many more miles you've traveled than the odometer says since you put the new tires on.
3. Keep in mind that your actual speed will be a few percent higher than the speedometer says. So if you were unhappy with your previous gas mileage at 55mph, adding a 5% larger tire and then drive where the speedometer still says 55mph, you will actually be going almost 58mph, and it's going to hit you with 10% more drag. You will have to be more careful if you like to abuse the speed limit, too.
Actually tires do weagh more than rims. At least in my application it does. My rims are beleaved to be 19 pounds and my tires I think are 24 or 25 pounds. And the weight of the tire place more into the picture since it is further out from the center and has more inertia. If you do a lot of highway miles I guess you could gain a very little by getting a little bit bigger tire. Just remember that when stopping and starting it will be that much harder. Odds are that you won't notice any difference in gas mileage, due all the reasons people posted above. If it was a tractor and had set gears with no tourque converter, then I could see that maybe it would help, but our cars are much more complex than that. The engine is contantly adjusting according to the strain on it and all the other variables that come into play. Also, higher performance tires tend to weigh a little more than non-high performance tires. Most tires that I buy, you can sit on when it is off the rim and it doesn't go down much at all. Regular touring tires will go way down when you sit on them. For me, I would rather add that extra .1 seconds on my 0-60 times just so I can go around corners at 25 mph instead of dropping way down to 10 mph like I had to with the stock Contis.
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
