See also All Wheel Drive considerations and Donut Spare Tires

Source: Tire Rack

A Mud & Snow (M+S or M/S) rating is a secondary designation and will appear in addition to other designations when a tire meets the RMA definition of a mud and snow tire.
This symbol designates a tire for severe snow conditions. (i.e. a snow tire)
See: NokianTires.com

For tires having a maximum speed capability above 240 km/h (149 mph), a "ZR" may appear in the size designation. For tires having a maximum speed capability above 300 km/h (186 mph), a "ZR" must appear in the size designation.

The Department of Transportation (DOT) requires each manufacturer to grade its tires under the Uniform Tire Quality Grade (UTQG) labeling system and establish ratings for treadwear, traction (The tire's ability to stop on wet pavement) and temperature resistance.

Treadware:
A tire graded 200 would wear twice as long as one graded 100.

LT Flotation (Light truck "flotation" tire, designed to deliver better traction on sand and soft soil found in watery off-road situations):
29X9.50R15LT [29 - Tire Diameter, 9.5 -tire's section width in inches]

LT Numeric (older sizing system is still used on older commercial vehicles):
8.00R16.5LT [8.00 = tire's section width in inches, 16.5 - rim diameter]

All-season	Performanced All-season	Ultra-High -Performance	Winter	All-terrain

Some other examples:
BF Goodrich Mud-Terrain T/A

Light Trucks, Jeeps and SUVs

Highway All-Season	Off-Road All-Terrain	Off-Road Maximum Traction (Mud-terrain)

https://www.miamipowerwheels.com/the-four-types-of-tire-tread-directional-symmetrical-asymmetric-and-direction-asymmetric/
See also: Different Tire Tread Patterns (Detailed Comparison)

See larger sizes at off-road tires.
Tire ratings below.

Tire Size:

Tire Sizes for Light Trucks at TireRack.com

• Changing to a larger diameter tire will have the following effects:
  
  • Raised center of gravity for better clearance at the cost of being more top heavy and prone to rolling over.
  • Like having a lower axle ratio for less power but better mileage.
  • Speedometer reading will be low. (ay be speeding ticket time!).
• Larger tires will be more prone to hydroplaning and have less traction in snow, however the large gap between treads will compensate for some of this in all terrain tires. According to a Jan. 2004 ConsumerReports article, a 245/40ZR18 tire (with 9% more contact area) will be 25% more likley to hydroplane and have 20% less traction in snow than a 225/55ZR16 tire, but will have a 4% advantage in wet/dry cornering and a 5% advantage in ice braking.
• Extreme plus-size truck tires put an even greater strain on brakes, wheel bearings, and suspension parts.
• Larger, grippier tires could also make some SUVs and trucks tippier by sticking rather than sliding under hard cornering forces and also during emergency road maneuvers.
• A March, 2004 ConsumerReports article describes a test comparing All Wheel Drive (AWD) cars with Front Wheel Drive using factor all-season and "winter" tires.
  Ice braking was virtually the same for all configurations.
  AWD cars accelerated to 20 MPH in 1/2 the distance of a FWD car with factory tires.
  Winter tires accelerated to 20 MPH in 2/3 the distance of all-season tires on a FWD car.

Larger wheels (rim to rim) are usually paired with lower profile tires (shorter sidewall) to get the same total diameter to avoid a total larger tire diameter (tread to tread) which will require that you change your speedometer and possibly gearing. The three combinations to the right all result in a 25 inch tread to tread measurement. See above for how it is measured.

  Low profile tires give better performance because there is less sidewall distortion on corners, so more tread stays on the road and they respond quicker.
  On the other hand, a low profile tire usually has a stiffer ride than a standard tire because there is less sidewall flex on bumps.
  Larger tires may decrease mileage because of they are heavier. A Car and Driver magazine tests showed mpg going from 22.8 to 21.9 with 18 vs 17" wheels.
  Because there is less flex in the sidewall on a low profile tire, a bump against a curb may distort the bead where the tire connects to the wheel rim, causing a loss of pressure.

Can and Driver says,
"Subjectively, both the 17-inch and 18-inch wheels and tires were in the sweet spot of grip, braking performance, ride comfort, and steering feel. Moving from 17-inchers to 18s barely degrades ride quality, and the additional grip is welcome."

Some Examples of tire options on popular cars:

	Standard	Optional	Total size
Subaru Outback	P225/60HR17	P225/55HR18	25"
Toyota Camray	P205/65R16	P215/55R17
Honda Accord LX-S	P215/55R17	235/45R18
Honda Civic EX-L	215/45R17	225/40R18
Honda CR-V	225/65R17	225/60R18
Honda HR-V	215/55R17

Off-road vehicles like jeeps may use a 15 inch wheel with a high sidewall to result in a 33-35 inch total diameter giving maximum grip at low pressures used for rock crawling. Links:
Effects of Upsized Wheels and Tires Tested - Tech Dept. - Car and Driver
What We Should Know About Tires: | jags.com
Are Low Profile Tires Worth It? - Straight Dope Message Board

Rolling Resistance and Tread life effect on cost:

They say the difference between the mileage from the worst to the best rolling resistance is 3 MPG (miles per gallon). So a one rank change in rolling resistance rating from good to fair could be 0.6 MPG at a gas price of $3/gal. and av. 20 MPG with a 60,000 mile tire that could be $65 in gas per tire over the life of the life of the tire, increasing the cost from 50-66% for a change of one rating or more than doubling the price of the tire for a two rank (very good to fair) change.

Tire Rack will ship tires to local dealers you can lookup on their web site where they will mount and balance the tires and dispose of the old tires for about $25 per tire. I found the price to be about the same as buying locally.

Tire										Rating score
										Tire Rack	Consumer Reports
Hankook Optimo H727	$96	4	4	4	4	4	3	3	3	99	82
Toyo Versado LX	$91	4	3	4	3	4	3	5	3		76
Cooper CS4 Touring	$86	4	3	5	3	3	3	3	2		72
Cooper Lifeliner GLS	$78	4	3	4	3	3	3	2	4		68
Toyo Extensa A/S	$99	3	4	4	3	3	3	3	3		76
Goodyear Assurance TripleTred *	$121	3	3	4	3	4	3	3	3	96	80
Cooper GFE	$83	3	3	4	3	3	3	2	4		76
BFGoodrich Traction T/A T	$90	3	3	4	4	4	4	3	2	95	74
Dayton Quadra LE	$86	3	3	4	3	3	3	3	3		74
Uniroyal-Tiger Paw Tour SR	$77	3	3	4	2	4	2	2	5	73	72
Michelin HydroEdge	$116	2	3	5	4	4	4	5	3	84	84

Tire	max 15" size	diam										Rating score
												Consumer Reports	Tire Rack
All Season
Firestone Destination LE	31x10.5	31	$115	4	3	3	4	4	3	1	2	66	86
Bridgestone Dueler H/L Alenza	265/70R15	29.5	$154	4	3	3	4	4	4	2	3	66	91
Dayton Timberline HT I	P235/70R15	28	$99	3	3	3	4	4	4	1	2	66
General Grabber HTS			$105	3	2	5	4	5	5	2	3	80	94
Michelin LTX M/S			$165	5	4	2	5	3	3	4	3	67	100
Goodyear Wrangler SR-A			$133	5	3	2	4	4	3	3	4	64	67
BFGoodrich Rugged Trail T/A			$127	3	2	2	3	3	3	5	3	53	71
All Terrain													Tire Rack
Pirelli Scorpion ATR			$163	3	2	4	4	5	3	3	1	79	98
Bridgestone Dueler A/T Revo			$143	4	2	3	5	4	3	2	2	71	99
Firestone Destination A/T			$112	3	3	2	4	4	3	3	3	66	100
Michelin LTX A/T 2			$158	3	2	2	5	3	4	5	3	68	99

See ratings at off-road tire page. (e.g. Hydroplaining, Handling, ...)

Air Pressure:

• Underinflation, by as little as 6 p.s.i., can cut gas mileage by 3%.
• OR EVERY 10 DEGREE FAHRENHEIT CHANGE In ambient temperature, your tire's inflation pressure will change by about 1 psi (up with higher temperatures and down with lower.)
• Use higher pressures for sustained high speed driving.
• THE TIRE PRESSURE RECOMMENDED in your vehicle's owner's manual or tire information sticker is a "cold" pressure, so it should be checked in the morning before you drive more than a few miles.
• Tires lose roughly 1 pound per square inch of pressure for every 10° F drop in outside temperature. You should check your pressures in Spring and Fall.
• A standard load tire with a normal inflation pressure of 35 psi may be branded with a maximum inflation of 44 or 51 psi, indicating the tire's ability to meet special vehicle performance requirements. It does NOT increase the tire's load capacity.
• 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.

• Tread is considered worn out when it reaches the industry norm of 2/32 inches deep (i.e. when you can see all of lincoln's head on a penny in the groove). CR tests have shown that tires typically lose much of their wet-weather and snow grip long before that. Recommendations are:
  In wet conditions 4/32 inch or more
  In snow 6/32 or more (recommended by TireRack).
• The Ultra High Performance tire that grips the track with tread temperatures of 200° is incompetent as its tread compound becomes like "hard plastic" at below 32°.
• Siping - Cutting small slits perpendicular to the face of the tire, which in turn creates thousands of tiny edges that help with grip to improve traction and braking. Along with those two benefits, it improves tire life by 15 to 20 % and helps the tire run cooler. The National Safety Council performed tests on tires that have been siped, and found that there was a 22% increase in traction on snow and ice.

  Consumer Reports tested two performance all-season tires, with and without siping.
  The siped version of both models showed modest but measurable improvements in snow-traction and ice-braking performance. But braking distances on wet and dry pavement were a few feet longer. Besides costing $60 or so for a set of four, having your tires siped potentially voids any tread-wear warranty. We donŐt think the modest gains are worth the extra costs.
  See: article af 4X4 review
  Article at Consumer Reports .

Some shops will take the tire off and put a patch over the hole from the inside. This will work if the thing that caused the leak was small enough so it didn't damage a cord
It will cost about $15.
But dealers will tell you you have to get a new tire.

Dealers:
Less Schwab
Tire rack

Glossary:
DOT - Department of Transportation

LR - Load Rating

NHSTA - National Highway Traffic Saafety Administration

PR - Ply Rating

RMA - Rubber Manufacturers Association.

Sidewall Types:
  BLK - Black, RWL - Raised White Letter
  WSW - White, OWL - Outlined White Letter

UTQGS - Uniform Tire Quality Grading System - A government-mandated tire rating system based on a tire's performance in treadwear durability, traction, and temperature resistance. UTQG ratings are branded on the tire's sidewall.

Tire Terms

Air Pressure at:
Tire Rack
Tire Wear and Pressure

Manufacturers:
Bridgestone
Dunlop
Michelin
BFGoodrich
Goodyear
See specific type links at the off-road tire page.

See Also:
Off-road tires and ratings at off-road tire page in recreation. formulas at TireRack.com
Recommended rim width
Substitute Sizes for tires
Tire labeling proposal at the DOT
Winter Tire Tech at TireRack
Tires at the National Highway Traffic Safety Administration (NHTSA) at the DOT