MIL-STD-878 Method Of Dimensioning And Determining Clearance For Aircraft Tires And RimsThis standard establishes the procedures for dimensioning and determining clearance for aircraft tires and rims.

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MIL-STD-8788

a.   The dimensions of new, unused inflated tires after a 12-hour inflation period

at rated pressure to remove initial tire stretch shall not exceed dimensions: DO, H, W, DS.

and WS.

b.   Provisions shall be made for tire growth represented by dimensions WG, DG, WSG, and DGS.  Tire growth is based upon the factors listed in Table I.

c.   Minimum radial and lateral clearances beyond tire growth limits are derived from Figure 2.

d.   Tire aspect ratios are obtained from Figure 3.

e.   The maximum shoulder dimensions shown as HS and WS shall be 0.82 of the maximum section height for all tire types, 0.85 of the maximum section width for Type III tires, and 0.88 of the maximum section width for Types VII and VIII tires.  Types III. VII, and VIII tires are described in MIL-PRF-5041 and MIL-PRF-7726.

f.   Radii WS and WSG are drawn through their respective shoulder points tan-

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gentially to DO and DG, respectively.  Radii below the shoulder points pass through the shoulder points and are tangential to W and WG, respectively.

g.   Dimension A, the wheel width between flanges, shall be obtained from Figure

3.

3.2   Definitions of Figure2.   Clearance allowance between the tire and the adjacent parts of the aircraft should be based upon the maximum overall tire dimensions, plus growth allowance due to service, plus the increase in diameter due to centrifugal force.  Minimum distances to adjacent parts of the aircraft should be determined as follows:

a.   Determine maximum grown tire envelope, i.e. the dotted line labeled "Grown

Inflated Tire"on Figure 1.

b.   Obtain radial clearance CR and lateral clearance CW from the chart on Figure

2.

c.   Determine distance to adjacent part as follows:

RX (minimum) = Radial distance from axle centerline (CL) to adjacent part = DG  +  CR

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WX (minimum) = Lateral distance from the CL to adjacent part = WG  +  CW

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SX (minimum) = Clearance allowed between tire shoulder area and adjacent

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