chalk test results

I have never done a chalk test so I would like your collective expert input.

I have been chasing a vibration issue in my truck since I got it lifted a few weeks ago. It is better but I can't stop paying attention to it. its like I can feel every pebble on the road. I have come to the conclusion that should have listened to all those people that said a lift, even 2.5 inches, needs a UCA replacement. Compound the fact that I am running stock UCA with the fact that the alignment shop could not adjust caster on the drivers side due to a frozen bolt. I am within stock configuration specs but on the low side for caster. It is not in the budget to get new upper control arms at the moment so I am looking at fixing other issues.

to that end, I did a chalk test last night in my driveway. I did not have a ton of time so I did a quick and dirty test.

my truck: 2011 tacoma DCLB 4x4 2.5/1.5 block leveling kit. MT 17 inch rims Cooper AT/3 285/70R17 tires road force balanced.

last night showed that at 37PSI I was over inflated on all 4 tires. (37 PSI came from the balance shop). I dropped the fronts to 33 and the rears to 32.

I did another test here at work today with a thicker stripe. iI can't tell on the front if I am good. I am not sure if I could under inflate a tire and still have the chalk test show good. what I don't know is, what should it look like for a well inflated tire? should it be perfect across the tire or do I want a slight taper towards the outside?

here is the front, hard to see but maybe this helps (I think that it is pretty good)



the rear to me seems like it needs more adjustment





would you agree that the front is good seeing as chalk is almost gone across most of the tire and the rear is still over inflated based on the outside treads? Does (cold) 33/30ish seem low for a 285/70R17 tire? it does to me....

One last question not related to this... My other problem currently is that I feel a hitch or notch in the steering near when the tires are straightening out. Kind of like at 10:30 and 1:30 on the steering wheel. it feels good up to that point. it shows up more at slow speeds but I can feel it at higher speeds also. Anyone ever felt this with a leveled truck? It did not do it before the level/tires. The universal joint on the steering shaft is in great shape. I don't feel any play in the steering wheel.... just a hic-up when straightening the wheel.

thanks

Carl

 

Interested in what you find I've been wondering if some of my shake is due to this

 

subbed...need to do a chalk test to!
I get a very small shake at ~55 and it stops at ~65 (and it's in the rear). It only appeared after putting the duratracs on. They had some balancing issues at the beginning so it could be a bad set of tires or my rear is over inflated...I'm running 37psi right now.

I do run stock UCAs but feeling every pebble came after installing the tires. To isolate possible issues, I ran stock tires for a while...so I know it is not the lift and alignment. Maybe it's just the fact that the tires are more aggressive as it seems to be no issue on certain types of road surfaces.

Again it's very minimal and drives great at 65+mph and below 55

 

its good to know that you do not feel the issue with stock tires/wheels.. I should have done that but parted out my tires for my wife's 4-Runner and sold the rims.

I was told by one of the 3 balance shops I used that my rims were crap. Three of the four were out of round. They gave me the truck back worse than when I left it so I am not sure I trust their opinion. the third/last shop that did a good job told me they had a hell of a time balancing, had to remove and move tires to different wheels to get the road force to work out. the difference was night and day but when you feel something bad it is hard to get it out of your head.

I believe that at the end of the day, I am going to find that the road feel is due to the bigger, wider, higher rated tires.

I can tell you that going from 37 to 33 did not solve all my problems but I did not fixate on the issue as much this morning as others. I need football to start up so I can pay attention to talk shows and take my mind off the feel.

I do need to get the steering fixed though. It could be the caster, just a guess. It could also be a problem in the steering that showed up when more stress is put on the system. not sure but I feel it too much and it is not right.

Carl

 

30-33 is low for those, i would try 35 all around, thats what I run with great results in a 265/75/16 duratrac

Also look into an alignment from a shop that specializes in them.

 

A couple things here.

1) that is the big question... if 33 is low then how am I misinterpreting the chalk test? The rear is currently 32 and based on all my tacomaworld research, the chalk test shows its over inflated.

2) I think there is a large difference between the tires you are running and mine.. I THINK I have thicker sidewalls due to the larger tire and the higher rating. that makes a difference in the inflating specs... but I would have thought the other way... I would have thought I should be inflated more than a smaller/thinner tire. I appoligize if I am wrong about your tire rating, I don't know anything about the duratrac.

3) I read a very good article on this site about why I want higher caster when lifting a truck. I think I want a caster of about 2.1 for a 2.5 inch lift, mine is currently at about 1. I wish I had read more before I budgeted and priced the level/tires... I probably would have stuck with stock wheels and used that money to get UCA's. it doesn't help that my caster can't be adjusted at the moment.

Carl

 

the rear is always much lighter so use less psi for that part of the test if you must or load the bed.

my rear end of the bed is much heavier than stock so 35 all around is perfect

 

After 100 miles on the expressway I can say "I think it feels better". I don't know for sure but it helped to convince me that my truck drives better so that is good. I was really hoping that someone experienced would give me a good feeling about my chalk test interpretation. If that does not happen I think I will keep all four at about 32-33 (cold) and call it a day.

 

I really think it's the duratracs...I like them and all but it made a huge difference. I think mine also got better with time and felt "softer" don't know if that makes any sense...mine are only C though.
Next tire I'll try the KM2 or KO2 but that's in a couple of years lol