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Passenger Tire sizing is typically displayed as:

P225/50WR17

• The "P" stands for "P-Metric" or "Passenger". This means that it is a North American tire sizing designation. European tires typically don't have the "P" attached to the size.

• The "225" is the width of a tire, also known as the "section width". This is the width of the tire in millimeters at its widest point from sidewall to sidewall.

• The "50"is known as the Aspect Ratio. It is calculated by dividing the section height by the section width and multiplying by 100.

• The "W" is the speed symbol.

• The "R" stands for Radial, meaning it has a radial construction. Other possibilities include "B" for belted construction and "D" for diagonal construction.

• The "17" stands for the diameter of the wheel in inches. This is the exact size that this tire will fit.

Information on upgrading your tires.

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The most common way of damaging tires is improper inflation. As tires lose pressure over time it causes them to experience irregular and early treadwear, and also give you poor gas mileage. Visually check your tires on a regular basis.  Ideally, purchase a quality tire gauge and make a habit of checking your tire pressure weekly.  Most accurate measurements are made when the tires are cold and have not been driven for at least an hour.

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The speed rating of any tire is a measurement of the top safe speed for any given tire. It is also an indication of how the tire will perform at lower speeds. A higher rated tire will give you better traction and improved steering response even at 50mph. Of course, higher the top safe speed, higher the cost.

Below is a listing of common speed ratings:

It is not recommended to downgrade your tires to a lower speed rating than of the OEM tires that came with your vehicle at the time of purchase. Also, never mix tires with different speed ratings on your vehicle.

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Plus 1:
Increase section width by 10mm
Decrease aspect ratio by 10 points
Increase rim diameter by 1 inch

Plus 2:
Increase section width by 20mm
Decrease aspect ratio by 20 points
Increase rim diameter by 2 inches.

The goal is to improve performance and appearance while maintaining overall diameter of the wheel/tire combination as close to stock as possible. This ensures proper speedometer and anti-lock braking system calibration, as well as unchanged fuel economy.

FOR THE 350Z:

The following tables show the different tire sizes which would result in a speedometer error of less than .5mph.  .5mph error rate was used to maintain as close to stock as possible.  However, error rates as high as 2mph are generally considered acceptable.

MODELS: Base, Enthusiast, Touring AT

Upgrade Front: 225/50/17 (Speedo error less than .5 mph)

Upgrade Rear: 235/50/17 (Speedo error less than .5 mph)

MODELS: Performance, Touring 6spd, Track

Upgrade Front: 225/45/18 (Speedo error less than .5 mph)

Upgrade Rear: 245/45/18 (Speedo error less than .5 mph)

Tire Upgrade Calculator

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Tires are typically replaced when their natural lifespan has come to an end. There are however any number of factors that can affect this including storage, temperature, surfaces they are driven on, how aggressive of a driver you are, punctures, etc.

The usual recommendation for replacing tires is when they no longer feel safe to the driver. You can see when they are worn out using the tread wear indicator. A typical set of tires under normal driving conditions will last approximately 40 000 miles or 64 000 km. Some tires of-course are designed for much longer, even up to 80 000 miles or 128 000 kilometers.

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Of note on the Track model of the 350Z is the super light aluminum alloy wheels.  These forged wheels (forging is considered to be the top construction method for high performance wheels) are manufactured by Rays Engineering and provide a weight saving of almost 8 pounds over the standard 18" aluminum alloy wheel.

Rays Engineering is a well known and respected manufacturer of aftermarket high performance wheels. Their most notable wheel, aside from the Track wheel on the 350Z, is the Volk TE-37, which has been the wheel of choice for the GT-R and Supra crowd.

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Positive offset means the mounting surface of the wheel is positioned in front of the true centerline of the rim / tire assembly. This in effect brings the tire in to the fender well more.

Negative offset is how most aftermarket wheels are designed. They move the center of the wheel away from the vehicle. Therefore, moving the tires away from the vehicle, and increasing the turning radius.  Increasing the offset puts more leverage on the lugs, which means you can break them easier, but it also increases the stance of your vehicle to help keep it more stable.

Benefits of Positive Offset:

• Less leverage on the lugs and steering linkage.
• Keep tires tucked under fenderwells.

Benefits of Negative Offset:

• Move wheels away from vehicle, when tires are rubbing frame during turns.
• Increase vehicle width, making it more stable.
• Some people like the "deep dish" look the wheel offers.

Wheel Offset Calculator

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Below are some simple instructions on how take care of your wheels:

• Make a habit of first washing the wheels when washing your car.
• Do not use household cleaners or other detergents to clean your wheels. The best wheel cleaning solution is a mild soap and water solution (whatever you would trust on the paint of your car).   Clean with a soft, un-abrasive cloth. Only on polished wheels can you use aluminum wheel polish. If you use this polish on chrome, painted, or clear coated wheels, you will only scratch the finish.
• Do not use steam cleaners in automatic car washes.
• Do not use any tire cleaners on your wheels.
• Clean wheels when they are cool. Heat can effect the soap, causing it to dry on the wheel and become difficult to rinse off.
• Clean one wheel at a time. This also prevents the soap from drying on to the wheel.
• After the wheels are clean and dry, apply a coat of soft paste style wax to them. This will create a moisture barrier and help ensure the finish lasts as long as possible.

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Use the following diagram for best torque distribution using the criss-cross pattern:

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Vehicle alignment is one of the most important factors in not only vehicle care, but tire care. Improper alignment on either the front or rear wheels can result in unusual tread wear, damage to your suspension, and unusual handling for the car.

There are several alignment types, including both two and four wheel alignment. Four wheel alignment is always recommended, but some vehicles are not able to have the rear alignment adjusted. Consult with an alignment specialist you trust to find out what's best for your car. Check your alignment often as many unexpected everyday factors such as hitting a curb, rocks, and potholes can misalign your wheels.

Warning signs include your car pulling to one side or another, and irregular tire wear.

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When mounting wheels & tires ensure the following checks are made:

• Wheels are not damaged in any way

• There is no dirt or oily build up between the hub and the wheel

• Lugs are properly torqued

• Both tire beads are securely mounted

• Any retaining clips on the brak drums are removed

Improper tire balancing can have adverse effects on your car and your safety. The most common signs of unbalanced tires are vibration and noise problems. These can affect the speed, handling and mileage of your vehicle.

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