Unsure what offset and backspacing to order..

Discussion in 'Lifted & Offroad Suspension' started by dmaiden38, Dec 8, 2010.

  1. dmaiden38

    dmaiden38 New Member

    I am currently trying to decide whuch wheel to order. I am installing a leveling kit in the front and 3inch body lift with add a leafs in the back. I am wanting to put 315/70/17 on a set of xd hoss wheels. I am wanting to try to tuck most of the tire under the fender. I dont want to use fender flares if i can get away with it i just dont want the side of my new truck tore up with rock chips. Here is my two choices of wheels that they offer. The first wheel is 17x9 backspacing 5.71 offset 18mm the second wheel is 17x9 backspacing 4.53 offset -12.00 mm. I need all the help i can get thanks Daniel
  2. stephan

    stephan Rockstar 4 Years 5000 Posts

    Hey Daniel, welcome to the GM truck club. This link will help get you rollin in the right direction.... As far as measuring your individual vehicle for proper clearance you should do both the lifts first, then do all your measurements for backspacing & clearance to everything before ordering your wheels.

    Backspacing and Offset

    Before mounting a set of aftermarket wheels, there are some dynamics involved with fitment that are best to understand first.
    1. Wheel Diameter. This is the diameter of the wheel. Stock wheels are commonly 15 or 16 inch diameter. This dimension is usually in 1 increments (i.e. 15, 16, 17) but some manufacturers offer 16.5, which is rare.

    2. Wheel Width. This is the width of the wheel, measured inside the outer lip of the wheel. This dimension is usually in 1/2 increments (i.e. 7.5, 8)

    3. Wheel Center. This is the center of the wheel in relation to the width.

    4. Offset. The distance from the centerline of the wheel to the face of the mounting surface of the wheel that contacts the hub4.1 Zero Offset. Indicates the mounting surface is at the wheel center.

    4.A. Negative Offset. Indicates the mounting surface is behind (or inboard) the centerline of the rim. This is often found on standard rear-wheel-drive vehicles and on so-called reversed rims. (Diagram below shows negative offset)

    4.B Positive Offset. Indicates the mounting surface is in front of (or outboard) the centerline of the rim. This is often found on front-wheel-drive vehicles. Stock Tacoma wheels have Positive offset.

    5. Backspacing. The distance from the mounting surface to the inside lip of the wheel. This measurement is closely related to offset (without actually measuring, backspacing is about equal to [Wheel Width / 2] + [Offset] + [about 1/4] ).

    6. Centerbore. The centerbore of a wheel is the size of the machined hole on the back of the wheel that centers the wheel properly on the hub of the car. This hole is machined to exactly match the hub so the wheels are precisely positioned, minimizing the chance of a vibration. This measurement may be critical to clear the hubs of a 4WD.

    7. Bolt Circle. Also known as PCD (Pattern Circle Diameter). The bolt circle represents the diameter of an imaginary circle that goes through the center of the bolt holes. 4x2 Tacoma Bolt Circle: 5 lug on 4.5 PCD; 4x4/Prerunner Tacoma Bolt Circle: 6 lug on 5.5 PCD.​
    (Diagram: Alloy Wheel Cross-Section)

    99'HEARTBEAT MODERATOR Staff Member 5+ Years ROTM Winner 1000 Posts Platinum Contributor

    To add what Stephan has posted,

    Starting with the tires.....they have a Overall diameter of ....34.4ins" and a Section Width of....12.4 in's...

    On the 17/9ins' Rims with a Backspace of 5.71.......the rims will be....1/2 in closer to your Suspension and Brake's....than Factory Rims

    On the 17/9in Rims with a Backspace of 4.53....the rims will be...2.7ins farther out than Factory Rims.....

    .....also your Speedometer will off....with the Tire size you have mentioned.....went it reads 60 MPH......your actual speed will 65.2 MPH......you'll need to have your Trucks computer Recalibrate.....for the new tires.


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