Shift Pointers: Failures caused by incorrect tire sizes - Transmission Digest

Shift Pointers: Failures caused by incorrect tire sizes

For years ATSG has produced a wide range of issues related to improper tire sizes on vehicles. Even under-inflated tires have been known to cause issues. Problems such as premature failure with an active 4WD transfer case will occur with incorrect tire sizes.

Additional issues include the following:

  • AWD vehicles can be negatively affected as well causing a binding wheel hop type of a feel while in turns.
  • Incorrect tire sizes affect 2WD cars that have curve recognition programs.
  • Curve recognition programs monitor the lateral movement of the vehicle to prevent shift busy-ness while in turns.
  • Incorrect tire sizes provide a false signal that the vehicle is in a turn when it is not. This will impede shift scheduling.
  • Under-inflated tires have been known to cause quirky coast downshift bumps and clunks.  

As a result of some of these issues, we often mention the use of a stagger gauge as a quick and easy method in checking the tires’ circumference (see Figure 1, above).

Aside from a stagger gauge being inexpensive to purchase, and how easy it is to use, what makes it such an effective tool is that it checks these tires with the full weight of the vehicle on them. This allows for a very accurate measurement. The idea is that all four tires should be very close in rolling radius. Generally, they should be within 1/8- to 1/4-inch of each other in circumference, not diameter. However, there are some vehicles that require the front and rear tires to be different in circumference.

As a sneak preview of ATSG’s 2024 Technical Training Seminars, one of the pieces of tech that will be presented is an incident that occurred with John and Dominic from Affordable Transmission Specialist. They had a local dealer send to them a 2010 Mercedes E350 W212 chassis equipped with a 722.9 transmission and 4MATIC transfer case with a complaint of a grinding noise. A road test confirmed the severity of the noise which was coming from the bearings in the transfer case unit. After the transfer case was rebuilt with new bearings and a viscous clutch, during a road test, the vehicle would exhibit a binding sensation on turns, just as if there were the wrong size tires on the vehicle.

When John and Dominic looked, they saw that all four tires were brand new and they were all the same size. They decided to look at the door jam sticker to see if the correct size tires were placed onto this vehicle. It was then discovered that the front and rear tires are supposed to be different in size. Figure 2 shows that the front tires are supposed to be 245/40 R18 while the rear tires are to be 265/35 R18. Instead, there were 245/45 R17’s all around (Figure 3).

Shift-Pointers-Jan-Figure-2
Figure 2.
Shift-Pointers-Jan-Figure-3
Figure 3.

These are completely different in both aspect ratio and circumference, causing the binding sensation on turns, damaging components in the transfer case. Once the correct size tires were installed, the 4MATIC function of the transfer case was restored which will also prevent repeat failure of the unit. So, with not all vehicles being created with equal tires, it is best to always compare the door tag information to the tires on the vehicle. A great lesson learned. 

Read more columns from our Shift Pointers series here. 

You May Also Like

Shift of the shaft: Diagnosing Chrysler 48RE manual shaft issues

The TorqueFlite transmission has been around since mid-to-late 1950s. There have been many changes surrounding the manual shaft and rooster comb through the years. This transmission shaft controls the position of the manual valve that directs oil for the gear ranges, but it also is used for a Reverse light control as well as Park/Neutral

The TorqueFlite transmission has been around since mid-to-late 1950s. There have been many changes surrounding the manual shaft and rooster comb through the years. This transmission shaft controls the position of the manual valve that directs oil for the gear ranges, but it also is used for a Reverse light control as well as Park/Neutral safety control. As it evolved, changes to these safety backup switches caused extra stress against the rooster comb that posed new challenges to the technician. 

Sometimes, a diagnostic code is all you need

With ATSG having the opportunity to help shops solve problems, sometimes we get faced with some real doozies. A shop will call and give us a laundry list of DTCs, leaving us to think someone must have a bulkhead connector unplugged. We then go through the arduous task of deciding which codes prompted other codes

10L80 and 10R80 pump gear differences

You may have seen an article in the August 2023 issue of Transmission Digest called “GM 10L80: A new kind of pump noise,” which goes over how the front cover housing in the 10L80 is fitted with a converter drive gear and idler gear. The idler gear drives the pump’s driven gear, and is press

Shift Pointers: What to do when the 62TE TRS tab breaks

How frustrating it is when on a hot summer day, as you go to open a nice cold can of your drink of choice, and the tab breaks off? You are outside, away from any tools to remedy the problem quickly. It now requires a MacGyver mentality looking around at the resources available to get

Going the extra mile: Proving your transmission repair suspicions

A 2003 Honda Pilot with a five-speed three-shaft transmission came into our shop with a customer concern that the vehicle had no power, and the “D” light was flashing. I first did a scan for codes to see what it came up with, and the scan tool returned four DTCs: P1298 (ELD voltage high), P0135 (H02S

RRfeature-1400

Other Posts

ATSG shop management training seminar coming soon

ATSG announced that it will soon be holding a series of management training classes for shops, beginning at the end of January. Related Articles – Are you down with CVT? – Shop Boss adds new user interface to its shop management software – How seriously should shops take the EV wave? Jonathan Sherman’s Management Training

ATSG-Sherman-1400
Spotting different 68RFE designs through the years to avoid issues

The Chrysler 68RFE has had several changes through the years. Its four-speed predecessor began with a noisy solenoid pack identified by a black colored pass-through case connector (seen in Figure 1).  Related Articles – Valve body and component suppliers: A comprehensive list – Understanding lube flow control valves in Toyota/Lexus UA/UB80 transmissions – How reading

Valve body and component suppliers: A comprehensive list

Looking for a comprehensive list of the industry’s valve body and valve body component suppliers for 2024? TD has you covered. Below, find a list of suppliers including contact information, addresses, etc. Related Articles – Sometimes, you should sweat the small stuff – Fabricating frictions: Keeping ahead of the curve at Raybestos Powertrain – Shift

Transtar launches Transmaxx brand of remanufactured transmission products with ETE Reman

Transtar Industries announced that it is launching a new line of remanufactured transmission products, the Transmaxx line. Related Articles – Force Control Industries releases transmission fluid for oil shear clutch and brake applications  – TransGo introduces 62TE high pressure kit for vans – OTC releases TJHP15 transmission jack  To begin the Transmaxx line, Transtar partnered

Transtar-Logo