Too Heavy

[bobsals]

Greetings, when I got my new 2012 F-350 last fall, one of the first things I did was remove the wheels and coat the back of the wheel mating surface with never-seize to keep the wheels from corroding to the hub. When putting the wheels back on, I couldn't lift them. Thought I was getting weak in my old age, but then decided to weigh them. Each wheel weighed 105lbs!
The only thing I can think of why they weigh so much is the wheel and tire must weigh 25 pounds, and then the 80 pounds of air make them 105.
Seriously, I know they are the 20" aluminum wheels but would never expect them to be that heavy. A couple years ago I bought a set of hydraulic wheel lifts from Harbor Freight. Glad I had them because the wheel lift made easy work of putting the wheels back on. The wheel lift also allows you to rotate the wheel to align the lugs with the holes. Thought I would pass this on in case there are any more weaklings out there beside me.
http://www.harborfreight.com/1250-lb...lly-67287.html

[DQDick]

Thanks for the info. I imagine I'm not the only one to get older and discover "I'm not the man I never was"!

[nosticks]

Yep Bob, I have those 20" wheels and tires. So far I have not tried to lift one, but hernia city is not what I'm looking to do.

[Slufoot733]

I learned how heavy my wheels were on my '08 F-350 the first time I did my own rotation. Oh my ache'n back! And mine are 18", not the 20's you have. Without a wheel lift I have to adjust my floor jack so I can line up the studs and lean the wheel into place. The heck with nthat lifting stuff!

[Tom S.]

I haven't reached the stage of needing one yet, but I can see it coming!

[bethandkevin]

A small pry bar used with a block of wood under the outer edge of the tire works well too Once on the hub on the rear you can turn the wheel to line up the studs. On the front same procedure except turn the rotor to line up the studs.

[Art-n-Marge]

I'm afraid 80psi is not the same as 80# of air in a tire. The wheels/tires weigh much more than 25 lbs when there's no air. But I understand what you're getting at.

Every 5,000 miles I change the oil, oil filter AND rotate my tires by myself. It's a struggle with the weight of the tires but I can still do it and it seems more of a struggle each time, but I think it will still be a while before I have to give it up. I don't think each tire weighs 105 (maybe 75#) and I kinda don't wanna know. I sit on a creepie crawlie to help position the tire onto the studs and use my legs to help position the tire into place. I like doing my own work because it's also when I check brakes and other stuff like that.

If could be worse. I had a big Mercedes and putting the wheels back onto the hub was harder because instead of putting the wheel/tire onto studs (then tightening down nuts after the weight of the wheel was on the studs), the wheels were held on by bolts. So one had to balance the wheel/tire and try to keep it steady enough to thread the bolt through the wheel and into the hole while balancing the weight of the tire with one hand. NO FUN. I'm glad I never had a flat on that car when out and about!

[bigskyjimmy]

Glad I still have 16 in wheels they are cheaper and lighter, I do not know why they started putting 18's on rigs?? I mean I put 18's on my sports car because they look better but the ride is harsher

[Tom S.]

quote:Originally posted by Art-n-Marge

I'm afraid 80psi is not the same as 80# of air in a tire. The wheels/tires weigh much more than 25 lbs when there's no air. But I understand what you're getting at.

Art, I'm pretty sure that was a tongue in cheek comment by him about the air weighing 80#.

[mlh]

I like the 20 inch wheels the tires are 65 profile and a little more stable than the 18s since they are only about 3\8 inch larger in diameter. When I bought my truck the wheels were a no cost option but the tires were $1000 extra, I think.
Lynwood

[bobsals]

About six years ago I bought a 550lb scale from Cabelas for weighing my propane tanks.
Cabela Scale
It's not a precision scale but it's been pretty accurate for weighing propane up to now. Yes, I was surprised as to how much the wheel weighed so I weighed it again and got the same thing. Could be off by a few pounds, but I think it's pretty close.

[Tom S.]

If you were to separate the tires and wheels, I suspect the tires would weigh around 60 to 65 pounds and the wheels make up the rest. Aluminum is light weight, especially when compared to steel, but it's not as strong, so in order to meet the weight limit of your truck, it has to be a lot thicker than a steel wheel would be, and that thickness translates to increased weight. The air in the tire itself does have weight, but it's relatively negligible.

Below is the formula used to determine the weight of air in car tire. The end result was 13 grams of weight at 30 psi.

•Total weight of tire + wheel + air ~60 lbs = ~30 kg
•Inside diameter of tire 15" = ~40 cm = 4 dm
•Outside diameter of tire (actually the space inside the tire) 21" = ~50 cm = 5 dm
•Width of wheel 6" = ~15 cm = 1.5 dm
•Pressure inside the tire 30 psi = ~ 2 bar (that is, twice "standard" pressure)
•Temperature 25° C ("standard" temperature)

(I'm using dm = decimeters for length because I want to measure volume in liters, that is, cubic decimeters.)

Air, at "standard temperature and pressure" (STP), has a molar volume of 22.4 liters and an average molar mass of 29 grams, that is, one mole of air masses 29 grams and takes up 22.4 liters at STP. Since we're estimating a pressure of twice "standard," the volume of 29 grams of air will be only 11.2 liters.

To get the mass of air, we need the volume inside the tire. For that we use the volume difference between two cylinders, one representing the wheel and the other representing the tire mounted on the wheel. The volume of a cylinder is given by

V = p × radius2 × height
Remember that radius is diameter ¸ 2. For the wheel, the volume is given by p × (4 dm ¸ 2)2 × 1.5 dm = 19 liters (cubic decimeters).

For the tire mounted on the wheel, the total volume is given by
p × (5 dm ¸ 2)2 × 1.5 dm = 29 liters (cubic decimeters).

The volume difference is just 10 liters, which means that the air in the tire will mass about 26 grams, less than 0.1% of the total weight (30 kg = 30,000 g) we estimated for the tire + the wheel.

Because of buoyancy effects, the air will only weigh 13 grams, less than 0.05%! Also, the thickness of the tire is negligible for our purposes.

[rames14]

Wait professor, could you leave that on the board a while longer? I'm not done copying it into my notes.

[Tom S.]

quote:Originally posted by rames14

Wait professor, could you leave that on the board a while longer? I'm not done copying it into my notes.

Here's the Cliff notes version: Air don't weight much.


BTW: At work I was caled the Wizard, but never the Professor!

[kab449]

I changed my own at my service station and I replaced the tires with the same OE Michelin. I didn't weigh just the tire by itself but I can tell you they are one heavy mother of a tire. The rims were about half the weight of the tires. Took two weeks for the back to recover. Next time my son who runs the business will get the job. Just wanted to see if I could still do it.

[CORattler]

That's a good tip! Thanks!

quote:Originally posted by BethandKevin

A small pry bar used with a block of wood under the outer edge of the tire works well too Once on the hub on the rear you can turn the wheel to line up the studs. On the front same procedure except turn the rotor to line up the studs.

[gkidsdlite]

I am still in the working world and drive a truck. When making some deliveries the customer says just unload and put it over there. My reply "Sorry I have a 12 ounce weight limit" Sounds like retirement doesn't it?

[Ol Tanker]

Bigger rigs need larger axles. If you have an 8,000 capacity axle you can't get by with the old 16" G rated tires. You will need the 17.5" H rated tires and those are neither cheap, easy to find or light. I know, I've had to buy more than 6 in the last 7 years. Changed out 4 and lost two others. Did all the work and the tires / wheels are well over 100 lbs each. I learned long ago about the use of at least one lever to help lift onto the mounting point. Unfortunately I don't have hubs that protrude more than a quarter inch. Makes for a tougher job.

[DQDick]

Don't have the weights for LT tires on the larger wheel trucks, but do have the weights for the tires we might put on our rigs. Michelin XPS RIB LT235/85R16 LRE (rated to 3042lbs) Weight 55.41 #, Bridgestone Duravis R250 LT235/85R16 LRE(rated to 3042lbs) Weight 60#, and BFG Commercial TA LT235/85R16 LRE(rated to 3042lbs) Weight 44.44#. So you can bet the 18" versions are heavier.

[shovelhead86]

I use a steel sno-shovel (ya'll remember what that is don't you) to raise the tire and wheel. DW presses down on the shovel handle while I get it onto the studs. I have done it by myself but it takes a bit of hand-leg cordination.