Any idea why a CA smog shop would put my truck on a chassis dyno to do the smog check as opposed leaving it in park and putting the emmissions test thing in tail pipe like they used to ( at least that's what they did to the last car I took in about 10 yrs ago)

The guy asked what size tires I had and when I told him 36's, he turned me away saying that he wouldn't put anything bigger than 33's on the dyno for safety reasons (that I understand).

 

Im not 100% sure if I understand.

But here the cars are put on rollers (rear tires only for rwd, front tires only on fwd and all wheels on awd) and then the imssions test begins. Starts with the idle test, then they have to put the engine under load so thats why they use the roller things.

That help at all?

 

thats just the way it goes. damn you better have regeared if you have that big of tires. i have 31's....

 

when i smogged my truck last march it was on the rollers. gray davis really beefed up the smog laws while he was governor, so that probably has something to do with it.

 

That makes sense about the truck being under load. Now I just need to find a cheap set of stock rollers to keep around for when I have to smog it every 2 years.

 

Its based on where you live, wether not you need the dyno. If your in a heavy populated area, hence polluted, they want the extra step. Here in Santa Cruz they don't do it normally. When I lived in Alpine county, Near Tahoe, there was no smog for residence.

 

Yep, your area must have come under the enhanced smog check program. Map from the Air Resources Board site:
- http://159.145.15.175/ftp/pdfdocs/program_map.pdf