# Do airliners use light alloy wheels, like cars do?

Do large and small airliners - up to jumbos like the Boeing 747 and Airbus A380 - use light alloy wheels in their landing gear to reduce weight?

If not, why not? Are there reasons unrelated to weight? Do extreme temperatures and rapid temperature changes affect the material in a way that could pose a danger to the aircraft?

• What alloy? Carbon steel is alloy, too. Safe too say all metal used for any structures is one form of alloy or another. – user3528438 Sep 20 '17 at 16:17
• @securitydude5 Steel is an alloy to begin with. I don't know what exactly "alloy wheels" are, but when it comes to cars, that's a marketing term, not really an accurate description of what they're made of. – Daniele Procida Sep 20 '17 at 18:04
• All non-elemental metals are alloys. Alloy wheels, I think, originally just referred to wheels that were not chromed or ordinary steel; chrome requires a lot of upkeep, especially on wheels. Other ideas where they were lighter than steel wheels and less likely to 'freeze' to the rotor (which is not true depending on the alloy), but still could have that shiny look of chromed wheels. Mostly marketing like @DanieleProcida said. – RomaH Sep 20 '17 at 18:33
• @securitydude5: 150 passengers at a modest 65 kg each would be almost 10,000 kg. Assuming you mean aluminium alloy, density about 2700 kg/m³, vs steel, 7850 kg/m³, that means that you think that some aircraft have $10000 \times \frac {7850}{2700} = 29000 \; kg$ of wheels. Where did you get those numbers from? – Transistor Sep 20 '17 at 19:02
• Lufthansa says that a 747-400 wheel rim weighs 74.4 kg. It has 18 wheels [1x2]+[4x4] so that makes 1339 kg. Using Peter Kampf's figure of 100 kg/passenger all the wheels on a 747 weigh about 13 passengers. If you could reduce the weight of the wheels by 50% (and this is unlikely) you could accomodate six more passengers (without seats) not 150 as you thought. – Transistor Sep 21 '17 at 6:26

Here's a description of small aircraft wheels:

Available in 4", 5" and 6", these wheel & brake assemblies are cast from 535.2 aluminum alloy for superior strength and corrosion resistance.

And some info on 535.2 AL alloy http://www.matweb.com/search/datasheettext.aspx?matguid=9347211fc1e1476988dfee51d8241c3c

"Light alloys" would also include magnesium, which has been used in aircraft construction. These days, one might imagine a carbon composite.

Light alloys tend to lose strength at lower temperatures than steel, and are easier to bend. Magnesium and aluminum will support combustion.

Many places where lighter materials are beneficial, but wheel rims may not be one of them due to close proximity to heating from the brakes and stresses from landing, especially in larger aircraft.

• While I've no experience of larger aircraft, the wheel rims on the Piper Cherokee are certainly a non-iron alloy. Presumably an aluminium alloy of some sort, but I never had a chemical analysis done :-) – jamesqf Sep 30 '18 at 17:58
• They are coming into use on 18 wheelers as well. My trust in steel may be old fashioned, would like to see cost and strength per pound analysis. Aerospace applications certainly favor lower weight. – Robert DiGiovanni Sep 30 '18 at 18:43