So, here's the story:
I had my s10 blazer aligned at town fair tire, and now close to 8 months later, my front tires are completely worn out on the outer edge (i.e. no tread left, NEED to be replaced soon). Upon reviewing their alignment spec, I noticed that they aligned it according to a full size blazer spec instead of the s10 blazer spec.

My question:
How much different is the full size alignment spec as compared to the s10 blazer spec? Is it dramatic enough that it could chew up my tires rather quickly? (note, the front tires weren't new when the alignment was performed, but they had plenty of miles left on them i.e. there was still tread)

I'm trying to see if it's worth my time to argue with them to get a new set of tires discounted for their incompetence.

Thanks for your replies!

 

Basically there are 3 angles involved during an alignment: camber, caster and toe. Only two of them will cause the tire to wear if not within specs.** Incorrect camber will cause a smooth wear pattern on either the inside or outside shoulder of the tire. Incorrect toe will cause a jagged wear pattern on either the inside or outside shoulder. Camber and toe spec should be very close to the same from S series to K series. Caster might be different, but caster does not cause tire wear.

**Camber and toe can both be within factory specs and still cause tire wear. Factory alignment specs give a "desired" spec and a "tolerance". The absolute best tire wear will be when the "desired" specs are used. It takes time to get it perfect and some alignment technicians will not bother adjusting to the desired spec, and send it down the road with the attitude of "it's within specs, good enough".

 

Ok, the wear pattern I've experienced is the smooth wear on the outer shoulder which you said is caused by incorrect camber. Do you know where I can reliably get the numbers that correspond to the specs for either vehicle? I have no trouble believing that the town fair guys didn't do a great job, but I would like to have some knowledge of everything and proof of a bad alignment before I go in and make a stink about it at the store.

 

Just to clarify.... the smooth wear pattern for camber occurs only on one shoulder of the tire and it can be different side to side on the vehicle, it just depends how each side is adjusted. If both the inner and outer shoulders on the same tire are worn smooth, the tire is under inflated. Smooth down the center is over inflated.

There are web sites that sell access to the specs. You might also try a library, they might have the GM factory shop manuals. A good rule of thumb for camber is zero degrees, meaning the tire is perfect vertical, (plumb). Rule of thumb for toe is positive 1/16" to 1/8", meaning that the tires are slightly "pigeon toed", (pointing toward each other in the front). As vehicle speed approaches ~40mph, they spread out and point straight ahead. Toe may need to be "tweeked" from factory spec to find what works best for the type of driving you do. More highway driving requires more positive toe, city driving requires less.

 

A very good explanation of how all the adjustments work. thanks! And to be clear, my problem is that one shoulder has worn all the way down (smooth) while the other shoulder remains intact. I will have to look around more to see if I can dig up alignment specs. I did find a couple sites, but they were less than reliable.

 

Outside shoulder worn is too much positive camber, (top of the tire leaning outward). Inside shoulder worn is too much negative camber, (top of the tire leaning inward).