| Tires | |
2) Clearance and traction are the primary factors to consider when going off-roading, and the right tire will give you an increase in both.
If "Black and round" sums up the bulk of your knowledge about tires, then you could benefit from the following tire tips. The fact is, your tires affect how your car steers, starts, stops, sounds, feels and looks.
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Two things to keep in mind: 1) A taller tire gives more clearance under the differential and chassis; and 2) A wider tire (or change in tread pattern) gives you more traction.
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Four-wheelers frequently put 35" tires on their trucks because most trails recommend this size or smaller.
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If you choose to put tires larger than 31" on your rig, then you'll most likely have to lift your vehicle. In which case, you'll need to be aware of the lift laws in your state.
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Whenever you go to a larger tire size you should re-gear your front and rear ends to off-set the size.
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It's important to keep in mind that lifting your vehicle also raises its center of gravity, thus increasing your chances for roll-overs.
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Underinflated tires cause the engine to work harder. It's like riding a bike with low tires. It’s harder to pedal because of the increased rolling resistance.
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Underinflated tires wear faster, and they affect the steering and handling of your vehicle.
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Tires lose air at a rate of about a pound a month, which means if they weren’t checked since the last time you had the vehicle serviced (say 4 months ago), they could be several pounds low.
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Underinflation, by as little as 6 p.s.i., can cut gas mileage by 3%.
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Cold temperatures affect the air pressure in your tires. There is a loss of one pound for each ten degrees of temperature drop.
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Gas mileage decreases 1% for each 10 lbs of underinflation.
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Most 4-wheelers drop their tire pressures for the trail? Mostly for increased traction. The downside of low pressure is that your speed is limited. In fact, at speeds above 15mph your truck will appear to be lagging far behind its capabilities.
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Remember when you air down, you are decreasing your ground clearance several inches by reducing the working diameter of the tire. So you will be lowering your gear ratio slightly, as well as making the sidewalls of the tire more vulnerable to damage.
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Airing down tires is the easiest and most cost effective method of increasing your off-road performance.
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While it's common to lower tire pressure if you're going offroad, if you have 1/2" in the description of your wheel (i.e. 16.5x8 -- found on many newer SUVs), DO NOT reduce your tire pressure when offroad! The bead found on the 1/2" variety wheels is not deep enough to keep the tire on during 4-wheeling excursions if the pressure is lowered.
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Most manufacturers put "P" (passenger car) rated tires on 4WD trucks as well. Some put "LT" (light truck) tires on SUVs and four-wheel drive trucks, but most do not.
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"All-terrain" (AT) tread performs well under a variety of off-highway conditions and to some extent has closed the street/trail performance gap. The closed tread design is usually quiet on the highway, yet noisier than a street tire, and performs well on rocks, sand, and on the highway.
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The MT ("mud tire") is at its worst in rain and can be outright dangerous in icy conditions. Another possible disadvantage of the aggressive tread of the mud tires is that they have a tendency to be noisy.
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Only a small patch of tire touching the pavement at any given moment (called the "contact area") is solely responsible for keeping your vehicle under control. It's hard to believe that little contact area is only about six square inches in size!
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Siping is a highly effective and inexpensive way to improve traction. It improves tire life by 15 to 20% and helps the tire run cooler. Siping also leads to a 22% increase in traction on snow and ice.
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Every tire carries a US Dept of Transportation serial number on the sidewall (EX: DOT M6 RV T1HR 499). The last 3 digits are a date code indicating the week and year the tire was made. (EX: the 49th week of 1999). Since tires can harden and crack with age, you should steer clear of old stock and buy the freshest tires available.
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Under normal loads, you should inflate tires according to the vehicle manufacturer's recommendations, NOT the maximum pressure listed on the sidewall.
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For the most accurate reading, tire pressure must be checked when tires are cold; that is, before they have been run a mile.
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Not all tires measure out to be exactly what they say they are. To find true the tire diameter mark the bottom of the tire and rotate one revolution. Measure and divide the distance by pie (3.14) and you have the true tire diameter.