Nylint Rock Crawlers
 

Although not real tiny, I haven't seen any threads on the Nylint Rock Crawlers at Walmart. They have 1/18 and 1/6 crawlers based on the Jeep Unlimited and Scorpion MK I. See more at ....

http://www.funrise.com/brand.aspx?id=5

I have a Jeep in both scales. I haven't run the large one, but the 1/18 Jeep can really crawl. I wouldn't call these hobby grade, but they did a great job. There is another forum I'm on where they have been doing a lot of modding to these.