# Extraneous truck wheels

**URL:** <https://boards.straightdope.com/t/extraneous-truck-wheels/249977>\
**Category:** Factual Questions\
**Created:** [June 12, 2004, 3:50pm UTC](https://boards.straightdope.com/t/extraneous-truck-wheels/249977 "2004-06-12T15:50:06Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![injuneer](https://avatars.discourse-cdn.com/v4/letter/i/a5b964/32.png) [@injuneer](https://boards.straightdope.com/u/injuneer)\
**Post date:** [June 12, 2004, 3:50pm UTC](https://boards.straightdope.com/t/extraneous-truck-wheels/249977/1 "2004-06-12T15:50:06Z")

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I have recently noticed that many large trucks have sprouted an “extra” pair of wheels behind the front tires. These wheels are smaller than the rest of the truck’s wheels and can be raised and lowered to make/break contact with the road. What in the world are these extra wheels for? Are 18-wheels just not enough sometimes???

Many Gracias… 🙂

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**Author:** ![postcards](https://avatars.discourse-cdn.com/v4/letter/p/8e8cbc/32.png) [@postcards](https://boards.straightdope.com/u/postcards)\
**Post date:** [June 12, 2004, 3:57pm UTC](https://boards.straightdope.com/t/extraneous-truck-wheels/249977/2 "2004-06-12T15:57:55Z")

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[What’s up with the “extra” set of tires on 18-wheelers?](http://boards.straightdope.com/sdmb/showthread.php?t=260717)