in march i purchased a 2002 f150 xl 4.6 extended cab 4 x 2 with 102,000 miles. the first several tanks of fuel i was able to get about 18 mpg. i purchased some factory aluminum wheels and swapped the same 235/75 x16 tires. the mileage is now approx 20 with a high of 20.5. my driving is interstate/rural. is it possible for the lighter unspring weight to make a difference?

 

truck milage normally goes up 1-2 mpg during the early summer when it starts to warm up. done know where you lieve, but many norther states have a "winter blend" of gas for better starting in cold weather. the milage with the cold air normally goes down. about may 1 each year you will notice things get a little better. my 5.4 gets 15.5 in the winter and 17 in the summer on the highway.

 

i relocated from central NC to warrenton nc. the lighter weight probably does not hurt but i did not think about the season change.

 

You will see a milage increase with aluminum wheels because they are lighter.

 

The mileage difference will be all the more noticeable in stop and go traffic, as what you're changing is, essentially, flywheel weights. We're talking rotational weight here, and it makes more of a difference, per pound, than does any stationary truck part.

That isn't to claim you'll get better mileage in the city than on the hioghway but, instead, if the driver used the truck primarily in the city, then the mileage would increase more for the stop, and get the wheels turning again, style of driving vs. the highway driver, where the wheels are brought up to speed and, pretty much, kept there. But in both places you'll notice a difference in lighter wheels and, to some lesser degree, lighter tires of the same diameter.

Which, while I really don't mind the style, is why I question the 20" and 22" wheels (a lot more weight a lot further from the spindle/axle, so) on all the city cars. I'd like to fully test drive one of the pimped rides to see how much worse the braking and acceleration is.

 

Wouldn't catch me dead in one of those "pimped" rides.

It's all about moment of inertia . Unsprung weight has a much higher effect on acceleration and braking than does sprung weight. For example, if you had 4 wheels that total 100 lbs heavier than your current, it would affect your truck more than putting 100 lbs in the bed, which would become sprung weight. Moment of inertia works much better in the driveline (i.e. aluminium driveshafts, lighter, more centralized flywheels, etc, but also works on unsprung weight.

 

Ive driven a few trucks that had 20s on them and you dont really notice the weight. I should mention though that often 20s are made to be as light as possible, too light in my opinion. All you have to do is hit a curb once and the wheel is pretty much ruined.

 

I think most of us would have to drive it with the original wheels half a day, then have them changed over, to notice anything. Plus, with a V-8 like the 4.6 or, especially, the 5.4, it will handle a portion of the extra load pretty well - but that does't mean it isn't there. It doesn't matter if the 20 inchers are as light as my 16's ( I doubt many are), as the extra rotaional weight further from the axle throws exponentially more weight into the driveline system.

But then I've found most drivers are pretty oblivious to handling effects; quite happy to drive on shocks / struts that are past their prime, will buy only the cheapest brake parts, and they couldn't tell the difference between a sway bar end-link and a spoon.

I wonder how many of the guys crying in the main forums about gas mileage went and pimped up their trucks with 17", 18" or 20" wheels, lol?

Good discussion guys.

 

what do you guys think the weight difference is between a steel wheel and an aluminum wheels? do you really think a few pounds will make al that difference? why would for put 17 inc wheels with 265 tires on stock if it cost 2-3 mpg more compared to 16 inch 225????

 

I always get a kick out of people who put 33s on their trucks without regearing and then complain because they are only getting 14 mpg.
Granted, the engine is turning less rpms with the bigger tires but it has to work a lot harder to spin those tires because of how much heavier they are.

 

Very well put - bigger tires are going to negatively affect mileage every time, but regaering to bring the truck back into the correct RPM ranges and transmission ratios often makes the hit only 2 or 3 MPG.

Steel vs. aluminum?

If you're going to keep the truck long term, IMHO it is certainly worth considering getting lighter wheels (if you don't beat the heck out of your wheels offroading or, for some, hitting vurbs while parking).

Problems with lighter and smaller wheels - you have more sidewall to flex, reducing handling characteristics. But truckers got by for many, many years with 15" wheels, so it isn't like using a 15" or 16" wheel is going to directly make your truck roll over in a turn.

Personally I'd love some big offroad-racing wheels, but they're just too big for street driving and my small V-8 engine. The stock Ford aluminum wheels I have, 16" version, are impressively light compared to the steels that came off of the truck and, according to my buddy, to his S-10 aluminum wheel / tire set-up.

Anyone have the 16" Ford OEM wheel weights handy? I believe they had a few different 5-bolt aluminum styles per year, and one steel style, but I could be wrong on that.

 

Ive got 17" steelies on my '99 F-150 and they are heavy. I hate rotating tires! LOL