New tires and alignment problems!!

[67Cutlass]

Hello all! Great site here. Hoping someone can help me out with my truck. Sorry if its long winded.

 

I have a 2005 GMC Sierra 2500HD 4x4. 6.0L, 4spd auto, 59,000 miles. I love my truck!

I recently had new tires put on by Town Fair Tire with front end alignment. Money is tight here so I went with them.

I had Bridgestone LT 245/75 R16 tires on the truck (forgot model tire) and the truck always drove excellent. The tires had cracking on the sidewalls, treads were pretty low and the fronts would lose air slowly. So I wanted to replace them before going on a camping trip. They put Prometer LL856 LT245/75 R16 tires on.

After picking up my truck and driving home it felt like the truck was floating, drifting or wandering from side to side once in a while with the steering wheel straight. Go to pull my 2400 pound camper the next day and it was worse! It was all I could do to stay in my own lane constantly correcting to stay straight.

Go for test drive without camper on highway and still did same thing but I felt vibrations too. Get back from camping and go back to Town Fair Tire, tell them whats going on and truck not the same since tire change. They realign the front wheels and rebalance the tires. Truck felt a little better on way home but not the same. The wife even says it doesn't feel the same on a test drive out with her.

I compared the alignment paperworks from the 2 visits and noticed some discrepencies between the 2.

They list a Before & Actual on the alignment charts. I would think that the actual readings from the first visit would be the same as the before readings on the second visit but they're not. Example:

First visit; Front left Toe Before .19* After .06* Second vist; Front left Toe Before -.01* After -.03*. See what I mean? Shouldn't the first visit after match the second visit before? Am I wrong? Is their machine junk or out of calibration? Are the tires I got the problem or is it a combination of tires and alignment?

Any help or insight would be appreciated!!

I don't feel safe driving it anymore!

 

Thanks, Mike

[Babyhauler]

Good luck with this.

Do some basic tire info checking.

Not to 2nd guess your purchase, Is that a popular tire or their cheapest? We are all on budgets, so new tires should be better, safer than old ones. Google the tire & see what pops up.

1st on a 2500, are they the correct weight rated tires.

What is the pressure? Put them at the door sticker psi to see how it drives. Compare that to the max psi on the tire. I think that is an E range tire. If your old tires were worn evenly, you probably did not have an alignment issue, if not, you may have.

If nothing helps, see if they will upgrade the tires to something that is proven to work on 2500's.

Hope this helps and you may have done all of this already. I'm sure we have some tire experts out there that may have more tips for this application.

 

Babyhauler

[Doug_Scott]

Don't use toe settings to compare alignment numbers like that. The total toe should be very close to being the same though. If total toe was 0.18 before, then it should be close to that on the return. You say the return was a total of .09. That is about half what it was before. The change was about 90 thousands of an inch. With the truck being as old as it is, and with the mileage it has, that amount of change can be simply looseness in front end parts. What are the other numbers? As with the other post, what air pressures did you run before, and what are you running now? How about load range of the tires? Higher load range will generally be a stiffer tire, and that will be more "touchy" when compared to a lower load range tire.

[67Cutlass]

Thanks for the replys here.

Previous tires were Bridgestone Duravis M773II LT245/75R16 E range. Fronts were at 65PSI and rears were at 80PSI per factory sticker in the door jamb.

Can't really find any reviews or much info on the Prometer tires on the truck now. Pressure on new tires are set to door jamb specs. They are an E range tire. When I went back the second time they also checked tire balance which they said was off a little. To me it still feels like they're out of balance, vibrations felt over 30 and vibrates when letting off the pedal from any speed.

I see what you're saying about total toe. So here comes some numbers...

 

First visit: Front Total Toe; Before .51* After .13*

Second visit: Front Total Toe; Before .04* After .05*

Spec range : -.10* .30*

 

See a difference of .09* between first after and second before?

Another thing I noticed is that I can't see any front suspension parts that look like they've had a wrench or tool put on them for adjustments. Here's more numbers if it helps...

First visit only Front: Cross Camber: Before .1*, Actual .1*, Spec Range -.5* to .5*

Cross Caster: Before .3*, Actual .3*, Spec Range -.8* to .3*

Cross SAI: Before .5*, Actual .5*, Spec Range none given

Total Toe: Before .51*, Actual .13*, Spec Range -.10* to .30*

 

Second visit Front: Cross Camber: Before .0*, Actual .0*, Specs are same as above

Cross Caster: Before .2*, Actual .2*

Cross SAI: Before -.2*, Actual -.2*

Total Toe: Before .04*, Actual .05*

They also give the rear tires Camber and Toe numbers which are also different between the two visits.

 

Once again thanks for all the help and insight. I may have to upgrade back to my original brand tire if these problems persist. I just hate the thought of giving them more money that I don't have or even letting them touch my truck again! Should've went to Firestone like I was going to do in the first place.

 

Thanks again!

Mike

[67Cutlass]

Oh yea it was only 5 days between the two visits on the alignment numbers.

[Doug_Scott]

 

First visit: Front Total Toe; Before .51* After .13*

Second visit: Front Total Toe; Before .04* After .05*

Spec range : -.10* .30*

 

See a difference of .09* between first after and second before?

Another thing I noticed is that I can't see any front suspension parts that look like they've had a wrench or tool put on them for adjustments. Here's more numbers if it helps...

First visit only Front: Cross Camber: Before .1*, Actual .1*, Spec Range -.5* to .5*

Cross Caster: Before .3*, Actual .3*, Spec Range -.8* to .3*

Cross SAI: Before .5*, Actual .5*, Spec Range none given

Total Toe: Before .51*, Actual .13*, Spec Range -.10* to .30*

 

Second visit Front: Cross Camber: Before .0*, Actual .0*, Specs are same as above

Cross Caster: Before .2*, Actual .2*

Cross SAI: Before -.2*, Actual -.2*

Total Toe: Before .04*, Actual .05*

They also give the rear tires Camber and Toe numbers which are also different between the two visits.

 

 

Not sure why they do not give you camber and caster numbers per wheel. The cross camber and cross caster numbers are the differences between the two wheels. Cross caster is the same, except it pulls to negative side. More than half a degree difference may cause a steering pull toward the side with the least caster, generally you need about a quarter to half degree difference to offset road crown (assuming your area is mostly undivided roads). Camber is not used to offset road crown because camber affects tire wear. Caster is an angle that effects handling more than camber does. Increased caster will increase steering sensitivity. Too much caster will cause steering "wobble". Think of a shopping cart with that one front wheel that just rattles side to side uncontrollably. Not giving you individual numbers does not give enough information to give an opinion on the effect of the alignment on the handling of the truck.

See if they can give you the actual camber and caster readings per wheel. Also, rear wheel numbers are actually important as well. Just because it is not adjustable does not mean it is with spec.

 

Numbers being different is not uncommon. You have to consider that the numbers are so precise it would be very uncommon to get the same exact numbers on different days. The front wheels are placed on turntables. If one of the turntables has dirty bearings, or slides, that will cause slightly different numbers. The change in your toe numbers is minor, you are talking about 3/32 of an inch change. A sticking turntable can do that easy enough. Total toe is allowed to be -.1" to +.3". That is about a total of 13/32 of an inch. Don't get hung up on the toe difference, it is not really an issue.

 

Did they give you a thrust angle number?

 

Just so you know, SAI is not an adjustable setting. If camber is correct, then theoretically SAI should be within specs. If it is not, then you likely have bent spindle. SAI is also known as KPI.