Cadillac Owners Forum banner
  • Hey everyone! Enter your ride HERE to be a part of September's Ride of the Month Challenge!
1 - 9 of 9 Posts

·
Registered
cts
Joined
·
9 Posts
Discussion Starter · #1 ·
I live in an area where potholes are everyday´s Bread & Butter.

When new, my 2016 CTS went straight from the dealership to get new shoes ! Correct tires in nice 19” Rims. The joy lasted about 18 months.A lot of broken rims, and broken tires.

I went back to original tires in original rims. After blowing 3 Pirellis due to potholes (nigh visibility with rain filling potholes, I decided get a definitive solution and still enjoy my car, instead of buying an SUV:

I put in correct 18” Rims with a minus 1 tire size, this is:
245/45 18 tires, instead of 245/40 18.

573563


The solution worked wonderfully !!! the broken roads where I drive are now a delight, I do not have to drive looking everywhere desperately trying to find the new pothole of the day, ?
Then…. A problem…. At speed (over 50 MPH) with small variations on the road, with a bit of bouncing, or variations in asphalt when changing lanes, the car “decides” to point to a different lane, moves slightly to the right or left…

I reviewed and checked everything. No solution. My conclusion is the the new tires ½” (12mm.) higher than stock is affecting the ride, because it is more noticeable when the car bounces a bit.

I took the car to the dealership today, but I am betting they won´t point to anything different than: “… change the tires to original size…!

My request for advice to the experts in this forum:
Is there a way to calibrate the ride height sensors to adjust to the new tire (vehicle) height?

I really would appreciate your advise.

Gonzp
 

·
Registered
2018 CTS 3.6L AWD Premium Luxury, Previous: 2009 STS 3.6L AWD, 2003 DTS 4.6L
Joined
·
399 Posts
Just a (somewhat) educated guess, no.............
 

·
Administrator
2002 F55 STS, 2014 Explorer XLT, F-150s
Joined
·
74,536 Posts
The ride height sensors have nothing to do with actual "height" - they send data on body attitude to the stability and suspension control systems. Height is adjustable by spring changes. IF the car uses the additional Electronic Level Control (rear only) that compensates for weight changes in the rear seat and trunk and does not change suspension height settings.

About the only difference a slightly larger tire outside diameter would make is to offset the speedo readings - a larger OD tire than original rolls less revolutions per mile so the speedo reads slow for actual vehicle speed.

Alignment may be the cause of the lane wandering.
 

·
Registered
2014 CTS 3.6L AWD Premium
Joined
·
122 Posts
In addition to the alignment suggested by Submariner, here are a few other things to consider. Firstly, most roads are crowned in the center to allow for water/rainfall drainage, consequently all vehicles tend to pull to the right or left depending on which side of the crown you are driving. Secondly, you mention variations in asphalt and this could be a contributing factor because when large, loaded semi trucks travel these same roads in many instances after many years those trucks end up making depressions in the asphalt where the tires roll over and when you change lanes and your car tires enter one of those depressions it's like driving in a rut which makes your car wander. In many instances the road depressions are not noticeable but they are there and will affect the attitude of your vehicle.
 

·
Registered
cts
Joined
·
9 Posts
Discussion Starter · #5 ·
The ride height sensors have nothing to do with actual "height" - they send data on body attitude to the stability and suspension control systems. Height is adjustable by spring changes. IF the car uses the additional Electronic Level Control (rear only) that compensates for weight changes in the rear seat and trunk and does not change suspension height settings.

About the only difference a slightly larger tire outside diameter would make is to offset the speedo readings - a larger OD tire than original rolls less revolutions per mile so the speedo reads slow for actual vehicle speed.

Alignment may be the cause of the lane wandering.
Than you Submariner409 ¡
You are right. The height sensors detect relative wheel-to-body so, nothing to do with tire height.
So, I did a bit of research and the MagnaRide suspension really helps getting the car close to the ground. Found this excellent note on it (2003 !) 2003-corvette-technical-article-magnetic-ride-star-wars-meets-the-50th-car
The magnetic ride detects pitch, heave and body roll. In my case Heave is what is causing my problems.
Of course, before al this, I made sure the car is properly aligned, so I discard that source of failure. Furthermore, up to some 40 mph the car behaves perfectly… And the problem surfaced only immediately after the rin/Tire change… so…
As I mentioned, I don’t believe the dealership is capable of such diagnosis, so, I will check the correct connection of

the sensors, alignment and do more tests….
573657
573656
 

·
Registered
cts
Joined
·
9 Posts
Discussion Starter · #6 ·
In addition to the alignment suggested by Submariner, here are a few other things to consider. Firstly, most roads are crowned in the center to allow for water/rainfall drainage, consequently all vehicles tend to pull to the right or left depending on which side of the crown you are driving. Secondly, you mention variations in asphalt and this could be a contributing factor because when large, loaded semi trucks travel these same roads in many instances after many years those trucks end up making depressions in the asphalt where the tires roll over and when you change lanes and your car tires enter one of those depressions it's like driving in a rut which makes your car wander. In many instances the road depressions are not noticeable but they are there and will affect the attitude of your vehicle.
Thank you for your comments HUmmer5. While you are right on your considerations, my problem is that these are the same roads I always drive and the feeling after bouncing (heave) are almost scary.... I do believe something has changed in the electronics.... the feeling os somewhat simmilar to the feedback I get whith the "lane daparture" reaction of the car....

Will do more tests, and keep posting resutls here...
 

·
Registered
2018 CTS 3.6L AWD Premium Luxury, Previous: 2009 STS 3.6L AWD, 2003 DTS 4.6L
Joined
·
399 Posts
Have you tried experimenting with different tire pressures?
 

·
Registered
cts
Joined
·
9 Posts
Discussion Starter · #8 ·
The mistery was solved. @Submariner409 was absolutelly right.

The dealership did a "by the book" allignment and problem solved. It is curious that the car had an alligment (not in the dealership) and was behaving correcly, didn´t lean to either side, but, evidently something was wrong, and it was corrected at the dealership.
 

·
Registered
Current 2014 red CTS Vsport/ Black Raven 2013 3.6 ATS4 gone
Joined
·
3,559 Posts
This is good to know.I have had sort of this problem from day 1 swapping to 20's. Mostly the bouncing in the right rear. I have had an alignment but not the dealer. I also have a new wheel in the rear and new tires. It still does it. I'm going to bring it to the dealer for an alignment. But with the small snow tires and factory wheels everything rides normal.
 
1 - 9 of 9 Posts
Top