I just spent a few hours driving and noticed something: all 2- and 3-axle trucks have all same sized tires, but all 4-axle trucks have larger tires on the front axle. Why is this? All the 4-axle trucks I saw may have been the same model, with two axles in front and two in the back. I thought it is something to do with the steering mechanism, but I also saw 3-axle trucks with 2 axles in front, and they had all same size tires. Any ideas?
That’s pretty common on cement mixers which have a good portion of the load on the front axle. Mixers are often on soft ground on construction sites and the wider tires can better spread the load so as not to bog down.
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- Two reasons - some trucks - in the U.S, moving vans in particular - often use smaller tires in back to provide a lower deck height, and using larger tires in front provides a smaller turning radius (because there’s more room inside a larger wheel, the [larger diameter] front wheels can turn farther left or right before hitting their mechanical limits than smaller wheels of the same width could). - MC
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Interesting - thanks. It did indeed look like the tires on the rear 3 axles were made as small as possible, and the front one was larger because there was more room under the cab. These trucks had two axles in front though, with the larger tires on only the first axle. Wouldn’t you need larger tires on both of the front wheels if you wanted to increase turning radius?
It just surprised me because having to deal with different sized tires seems like a lot of trouble logistics-wise, having to stock and carry different sized spare tires, etc. I wondered what advantage was significant enough to overcome these inconveniences.