Officially April 30 is the last day you are allowed to be using studded snow tires on B.C. roads. As I am writing this on April 30, I am pretty sure there was a section of BC highways today on which studded snow tires may have been helpful. Who turned off the heat?
I have yet to take the snow tires off my vehicle but I definitely have it on my “to do” list. So should you.
This article is not about tires per say but more about wheels and the proper way to install them. You may do the winter summer tire changeover on your own or you might leave it to your tire shop or maintenance provider. In all cases you may or may not know that you are responsible to have the tightness of the bolts checked on your wheels not long after they are changed.
Many shops have a statement suggesting a mileage interval not to be exceeded after wheels were removed and reinstalled written on their invoices. Remember also that tire changeover is not the only time your wheels are removed and installed. Many procedures require the removal of your vehicle’s wheels. Brake work might be an obvious one but there are a lot more where wheels are removed to access other parts for maintenance and repair.
I don’t keep accurate statistics on this but it seems to me that more and more wheels are coming loose these days.
A rolling wheel will make noise when it is coming loose. It will start as a creaking noise that will develop into a wobble over time. Left loose for too long and parts will get damaged. Namely the wheel but also the studs or bolts that locate the wheel and allow it to be clamped to the hub.
Why so many loose wheels? I have some theories and I also know some facts. Changing tires and wheels may seem to be quite a simple job and many are only concerned with doing the job quickly and therefore profitably but the whole process requires care and training.
The wheel is mounted to a vehicle with typically five or more lug nuts or studs. The interface of the wheel to the brake rotor or brake drum, to the hub and wheel bearing is a sandwich. This sandwich must be free of condiments so to speak. The wheel must contact the drum or rotor precisely and the drum or rotor must be in precise contact with the hub. In preparing this sandwich the technician must make sure all the surfaces are clean and flat. No condiments means no dirt, rust, excess paint, grease, or anti seize can be present. Any material that gets stuck in the sandwich will create what is known as a soft joint. After the bolts or lug nuts are tightened, the rust, dirt or excess paint, grease and anti seize will compress or wear away and reduce the clamping force of the bolts or nuts allowing them to come loose.
Therein lies the problem when wheels are changed. The mating surfaces must be clean and flat. After winter, dirt and rust buildup is likely and time must be taken to clean it up.
Another problem arises with the wheel bolts or nuts. Different wheels many times require different bolts or nuts particularly when switching between steel and aluminum wheels.
Clean matching surfaces, correct nuts or bolts, time to check the threads and lightly lubricate them and torque to specification. The torquing process requires either a torque wrench or torque stick. Too tight is just as bad as too loose. Too tight will ruin the bolt or stud threads as well as warping brake rotors. Too loose; obvious problem. Don’t forget to recheck that torque 50 kilometers down the road.
Trail’s Ron Nutini is a licensed automotive technician and graduate of mechanical engineering from UBC. He will write every other Thursday. E-mail: email@example.com