Tire Wear as Indicator of Worn Suspension Parts, BMW MINI
Whether you drive in the seasonal snow areas of the country or live in a more southern or pacific coast area, you’ll either be swapping winter and summer tires regularly or installing new tires as the existing ones become worn. The following information applies to all of these scenarios, as we are removing the existing set of summer or winter tires or the set of worn-out tires, in preparation for a new or seasonally alternate set.
Here we are, in the north-east, winter is upon us and the first snows are rapidly approaching (or have already set in, for folks in some snow-belt or mountain areas). Our thoughts turn toward winter driving, both the fun of snow driving as well as the difficulties and inconveniences. For either side of these thoughts, we turn to our trusty set of winter tires, or snow tires as we commonly call them. Whether we are pulling them out of storage or purchasing a new set, during the installation is when we end up getting a good look at the summer tires (or the winter tires, when changing back to summer). Unfortunately, with our BMWs and MINIs, it’s not uncommon that we are greeted with a choppy, feathered, cambered or otherwise worn tread pattern; a pattern that is trying to tell us something. Uneven tire wear is a direct result of incorrect tire pressures, incorrect wheel alignment, worn suspension parts or excessively aggressive alignment settings (camber & toe, specifically).
Check these links for more details on tire wear and inspections:
Tire Care; Part-1
Before installing (or before putting too many miles on) our winter tires, we’ll want to take care of the sources of uneven tire wear. This may be a simple as being aware of and managing the tire air pressures. However, a full inspection of the control arms, ball-joints, bushings, tie-rods and shocks may be in order. Let’s take a look at some of the common tire wear issues and the possible common causes for the wear:
a) Feather edging - The tread blocks have sharply worn edges on one side of the blocks. If you rub your hand over the tread (in a circumferential direction – around the tire), the edges of the blocks will be smooth in one direction, but sharp in the opposite direction. Feather edging commonly causes tire noise. The noise can sound like a high or low pitched whine or even a rumble similar to worn wheel bearings. The most common cause for this is excessive toe-in or toe-out. Excessive toe-in/out can be caused by worn/loose control arm bushings or ball-joints or well worn wheel bearings, but the most common fault would be worn/loose tie-rod ends or improper toe-in alignment settings.
b) Cupping - Tread cupping appears as individual worn spots (or cups) on the tire’s tread surface. These worn/cupped areas are typically a couple inches to 3 or 4 inches in diameter. The most common cause of cupping is worn shock absorbers (struts). However, improperly balanced wheel/tire assemblies , worn control arm ball-joints and worn wheel bearings can also cause cupping.
c) Camber wear - Camber wear causes the inside or outside edges (one or the other, not both) of the tire’s tread to wear faster than the rest of the tread. The most common camber wear is due to negative camber. Negative camber causes the inner tread of the tire to experience accelerated wear and appears as a worn ring all the way around the inner tread blocks. Excessive negative camber can be a designed-in feature (to increase cornering abilities) or be due to incorrect alignment, worn upper strut mounts, ball-joints or control arm bushings.
d) Under-inflation - Wear from under-inflation is evidenced by the inner and outer edges of the tread showing accelerated wear. Under-inflation causes increased road pressure on the outer inner and outer tread blocks (vs. the center of the tire). This increased pressure results in the accelerated wear. The worn tread blocks are similar to camber wear but the wear is not limited to just one side of the tire’s tread.
e) Over-inflation - Over-inflation produces accelerated wear in the center tread area of the tire; sort of like a skunk’s stripe, and about as pleasurable. Just the opposite to under-inflation, over-inflation wears the middle tread blocks of the tire due to the increased road pressure on the center of the tread.
What to do?
If the tires that are being removed show signs of improper wear, do yourself a financial favor and inspect the suspension components before putting many miles on the new set. A bad wear pattern can develop in a little as a few hundred miles …. a pattern that you’ll have to live with for the remaining life of the tires.
Click links below for more details on vehicle and suspension inspections:
Worn suspension components are replaceable and readily available from BavAuto®. If a camber problem exists, special adjustable components may be required. BMWs and MINIs do not have adjustable camber at the front suspension and many do not have any camber adjustment at the rear. Those that do, have very little and may not be adequate to rectify a tire wear problem. BavAuto® offers the special adjustable suspension components that allow the front and/or rear camber to be properly adjusted for best tire wear (or best handling …. or a compromise between both).
Click below for BMW & MINI suspension parts:
Click below for BMW & MINI Camber correction kits: