FAQ: common questions and common answers.
Note: always consult your local dealer before purchasing any tires or wheels, or with any questions.
This unofficial information should not be used for tire, wheel purchase decisions or vehicle speed or weight capability. Always contact your local dealer.
Subject to change and correction without notice

Q. How often do I rotate tires?
A.   Every other oil change or so, thus usually every 6-10,000 miles. You want the tires to wear evenly for longer wear, better handling, and safety.

Q. Do I need to replace all 4 tires is I have a blow-out?
A.   Because full time all-wheel-drive systems read traction from the tires, mis-matched tires are a bad.
This means all tires need the same tread pattern and size to within 1/4" circumference?. The same tread pattern means they need to be from the same manufacturer. If you have a non-repairable blow-out and the tires aren't brand new you should replace all 4 unless there's less than 1/4" circumference difference.

Q. Why do my tires or steering wheel shudder or wobble?
A.   Either your tires are off balance or not aligned properly, or you have a suspension issues, but you get it inspected right away.

Q: Tire pressure monitoring, what is it? US (NHTSA) Safety regulations require all new 4-wheeled vehicles weighing 10,000 lbs or less to have with a monitoring system detecting a 25% drop in pressure on 2008 models.
A. TIre Pressure Monitoring Systems (TPMS) measures tire pressure using a small sensor inside each wheel. When a tire drops 25% in pressure a warning light on the dashboard comes on. You then need to check each tire to see which one is low.
Cold weather Tires usually lose pressure in the cold months so it's common for the light to come on in the first cold months.
Rotate tires No need to do do anything with the sensors for a simple rotation. The sensors are not wheel or position sensitive.
New tires The sensor(s) will need to be programmed if a tire is removed from a wheel.
2nd set of wheels  Get a set of sensors if you get a 2nd set of wheels and tires, example for winter snow wheels and tires, racing wheels and tires etc.
Emergency tire inflation cans The sensors do not like the emergency roadside tire inflation and repair cans that many people carry in the the trunk because the stuff that fills the small hole and seals tire so it can hold air also clogs the pressure pinhole in the monitor. The sensor will need to be replaced.
Watch for this warning light in the instrument panel.

Q. Should I use Nitrogen?
A.  Some dealers are offering Nitrogen is an alternative to inflating tires with normal outside air. It maintains tire pressure better than normal air which leaks out over time and is less sensitive to cold outside temperatures. As a result, Nitrogen minimizes the Tire Pressure Monitoring light coming on.
And because it maintains tire pressure better and is less sensitive to hot and cold, nitrogen can improve economy, increase tire life, and is safer because the tires are less likely to blow-out when driven at high speeds for a long distance, or on hot roads.
Nitrogen has been used by Nascar, Formula One, the Tour de France and the military for years.
Mixing air and nitrogen. Don't put normal air in a tire with nitrogen because you will lose the nitrogen benefit, but it's not dangerous.
The downside to Nitrogen is that you might have to pay for it (but air is free).

Q. How often should I align my car?
A.   As needed. If the car pulls, if the tires show uneven wear, when you get new tires.

Q. What kid of tires should I get? The tread pattern will vary according to road conditions, vehicle, your driving style and needs.
         Always contact with your local tire dealer if you have any questions and before making any purchase decisions.
A.  Wet climate (rain, snow etc)- M+S mud and snow is the most common for an all-around tire. All Subarus (exc STi) have M+S tires.
A.  Snow climate- studded or studless snow tire, or use chains (see below).
A.  Dry climate- summer tire.
A.  Performance- performance tires are available for most weather/road conditions

Q. What are Summer performance tires?
A. Summer tires were designed for warmer temperatures and high stress use. Because of this they have very large stable tread blocks that are not good in inclement weather. In addition the rubber compound does not maintain elasticity in cold weather. What this means is that the grip level of the tire degrades drastically in cold temperatures even on dry pavement. In the cold a summer tire becomes unpredictable and feels “slippery” when cornering no matter what the weather. This problem is compounded in wet or snowy conditions.

Q. What is siping?
A.   Siping is a diagonal slice across the tire that improves traction on wet or slippery roads. The slice 'opens' as it passes over the surface and helps grab the road as well as disperse water.

Q. Can I use tire chains on a Subaru?
A.   If you do a lot of winter driving, it's best to consider a set of winter snow/ice tires. Chains are not recommended on a Subaru, it's a clearance issue. Spider chains are ok because they don't go on the inside of the wheel. If you can't use those and absolutely must use chains, use 'Z' chains though again this is not recommended. Put on the front (or drive wheels if 2wd) and keep your speed down and make sure they're very tight.

top
 

top
 

UTQGS: Uniform Tire Quality Grading System Treadwear, Traction, Temperature Grades A US govt system helps you compare tires for tread wear life, traction (stopping), and heat. Of course many other factors impact tire performance including road and weather conditions, inflation pressure, vehicle weight etc as well as driving skills.

Treadwear Grade Measures the tread wear life and helps compare tires made by a same company. The higher the number the longer a tire should wear. A tire with a Tread Wear Grade of 200 should last twice as long as one with 100, 400 should last 2x as long as one with 200 etc, but different manufacturers might use different base numbers.  Traction Grade  Measures the stopping ability of a tire. The higher letter (AA) should stop better than a lower letter (A). The grades are, better to lower  AA, A, B, C. Temperature Grade A, B, C. A tire's ability to perform in hot conditions such as the high temperatures caused by driving a long distance in hot weather. This can lead to blowouts and tread separation. From highest to lowest, a tire's resistance to heat is graded as “A”, “B”, or “C”.

top

top

top

top

top

top

top

top

top

top

top

top

top

thank you.
top