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<02> Tire Size

TK Gustafson <[email protected]> wrote:

> does anyone know what the right tire size to get the correct 
> speedo reading on an '02 with 14" alloys?

Here are some tire sizes that might be used on an '02, listed in 
order of outside diameter:

                     (2)
                    Diff.
             (1)    from
          Diameter  stock     
Size      (inches)   (%)  Comments
*-------- --------  ----  ---------------------------------------
195/55-14   22.4    -1.3  (3,4,5)
175/70-13   22.6    -0.4

165R-13     22.7     0.0  Stock '02 size (except 2002 Turbo)
205/60-13   22.7     0.0  (7)
185/60-14   22.7     0.0
195/50-14   22.7     0.0  

205/55-14   22.9    +0.7  (7?)
205/50-15   23.1    +1.8  (7?)
195/60-14   23.2    +2.2  Stock size for some E30 (3,8)
185/70-13   23.2    +2.2  Stock size for 2002 Turbo
175/80-13   24.0    +5.7  Rubbing likely
195/65-14   24.0    +5.7  Stock size for some E30 (3,4,5,6,8)

Notes:

(1) Diameter is approximate.  It varies with tire manufacturer 
and model.  It also decreases about 1.1 % from new tread (10/32 
inch) to no tread (2/32 inch).
(2) Differential ratio is effectively reduced by this amount, 
e.g. with 195/65-14 tires the stock 3.64:1 ratio becomes 3.44:1.
Speedometer reading is reduced by this amount, e.g. with 
195/65-14 tires the speedo reads 61.5 at 65 MPH.  Speedo reading 
increases as tires wear (1).  Speedo reading varies with normal 
manufacturing tolerances, typically -2/+5 % IMO.
(3) Slight, occasional rubbing on front inner fender walls at 
full lock is common with these sizes.
(4) Slight, occasional rubbing on tie rod boots possible on tii.
(5) Slight, occasional rubbing on front fender lips is common.
(6) Slight, occasional rubbing on front apron is possible.
(7) Rolling, trimming, or stretching of fender lips is required 
for clearance.
(8) E30 ('84-'91 3-series) 14-inch alloy wheels fit '02s well and 
are a common upgrade.  If tires are included, try for 195/60 
rather than 195/65.  Replace steel wheel nuts with alloy wheel nuts.
(9) E21 320i wheels fit '02s poorly because of their different 
offset.

Comments and corrections are encouraged.

Curt Ingraham
[email protected]