Steel wheels and MPG... no change

[Manhattan]

I figured a report might be useful...

Yes, the Tundra steelies are heavier. So too are the 285/70/18 BFG KO2s. But, does it matter? I supposed in a lab setting it might. From my experience so far - 4,000 miles - I can't tell a difference.

I went from OEM 18s with 285/70/18 BFG ATs to 18" Tundra steelies with BFG 285/70/18 BFG KO2s. Off the line and braking - the 100 feels exactly like it did before. I tracked the mileage - on the highway - a few times, and the range of results is the same. This week, with my family of 4, fully loaded for a week at the beach (luggage, chairs, food, typical beach crap, etc.) and NOT caring about mileage, e.g. mostly in the left lane, 70-80 MPH... the trip average was 15.96 MPG. Granted that was 100% highway.

On the highway, the heavy wheels really don't make a difference - rotating mass hurts acceleration and braking. Turning too. The big caveat here is that I haven't (and likely won't) track in-town MPG, where the heavier wheels would (could) make a difference. I mean really, if I was going to sweat a drop from 9.6 to 9.5 MPG... I'm driving the wrong vehicle.

But, as I argued in a thread a while back... if the steel wheels were such a gas hog around town, why don't we see light-weight alloys on UPS and FedEx trucks.

 

[mcgaskins]

From someone who ran stock wheels with 33" Duratracs and went to Tundra steel wheels with slightly smaller BFG ATs and drove almost exclusively in the city I can tell you it DID make a big impact to fuel economy and was much, much harsher riding on city streets. It not only felt slower and heavier to accelerate, decelerate and turn to me, but it did to my fiancee riding in the passenger seat! When she drove it, she actually hated it. That's why they came off and I went back to stock. You may have experienced something different, but I don't want people thinking your experience is likely to be theirs.

I'm sure UPS and Fedex trucks use steel because they're easier to repair which probably happens a lot. It's probably much easier and cheaper to buy tens of thousands of steel wheels able to support massive loads than it would be to buy and replace alloy wheels since they can't be repaired easily like steel.

 

[Sandroad]

There are other factors besides mpg to consider. The Tire Rack Wheel Tech info on alloys compared to steelies doesn't mention mpg, but has important other differences. Some of these may not be relevant to the typical LC use, but some are.



Tire Rack Wheel Tech:


A vehicle's total weight is the sum of all of its parts and affects its ability to accelerate, brake and corner. Reducing the total weight will enhance the vehicle's performance because less weight needs to be controlled and therefore, less energy is required. Unsprung weight is the weight under the springs which moves up and down as the vehicle rides over uneven roads and leans in the corners. Reducing unsprung weight allows the springs and shock absorbers to be more effective in controlling the suspension's movement. Additionally, a vehicle's rotational weight includes all parts that spin including everything in the vehicle's driveline from the engine's crankshaft to its wheels and tires. This affects the energy required to change speed as the vehicle accelerates and brakes. As you would guess, reducing the weight of any of these rotating components will enhance the vehicle's performance because less energy will be required to increase or decrease their speed.


Reduced Unsprung Weight Compared to Steel Wheels


This is one of the most critical factors affecting a vehicle's road holding ability. Unsprung weight is that portion of a vehicle that is not supported by the suspension (i.e. wheels, tires and brakes) and therefore, most susceptible to road shock and cornering forces. By reducing unsprung weight, alloy wheels provide more precise steering input and improved "turning in" characteristics.


Improved Acceleration and Braking


By reducing the weight of the vehicle's rotational mass, alloy wheels provide more responsive acceleration and braking.


Added Rigidity


The added strength of a quality alloy wheel can significantly reduce wheel/tire deflection in cornering. This is particularly critical with an automobile equipped with high performance tires where lateral forces may approach 1.0g.


Increased Brake Cooling


The metals in alloy wheels are excellent conductors of heat - improving heat dissipation from the brakes - reducing risk of brake fade under demanding conditions. Additionally, alloy wheels can be designed to allow more cooling air to flow over the brakes.