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275/70R17 vs 35x12.50R17

35x12.50R17 is +2.84″ in overall diameter and +43 mm in section width against 275/70R17 — a diameter change of +8.84%, which breaks the ±3% substitution rule. An indicated 60 mph would really be 65.3 mph.

Outside 3%

Every dimension

Difference between 275/70R17 and 35x12.50R17
Dimension275/70R1735x12.50R17Change
Overall diameter32.16″ → 35.00″+2.84″ (+8.84%)
Section width275 mm → 318 mm+43 mm (+15.45%)
Sidewall height192.5 mm → 228.6 mm+36.1 mm
Rolling circumference101.03″ → 109.96″+8.93″
Revolutions per mile627.2 → 576.2−50.9
Axle height / clearance16.08″ → 17.50″+1.42″
275/70R17275 mm
35x12.50R17318 mm
Scale drawing comparing 275/70R17 and 35x12.50R17, both standing on the same ground line
275/70R17 32.16″35x12.50R17 35.00″

Which is taller, 275/70R17 or 35x12.50R17?

35x12.50R17 is the taller of the two, at 35.00″ against 32.16″. The gap is 2.84 inches, or 72.2 mm.

One of these is a flotation size, which states its overall diameter on the sidewall, while the metric size only implies one — so the comparison is between a stated height and a derived one. 275/70R17 is 275 mm wide with a 192.5 mm sidewall on a 17 wheel; 35x12.50R17 is 317.5 mm wide with a 228.6 mm sidewall on a 17 wheel.

What the speedometer will read

Indicated versus actual speed after the size change
Speedometer readsActual speedError
25 mph27.2 mph+2.2 mph
40 mph43.5 mph+3.5 mph
55 mph59.9 mph+4.9 mph
60 mph65.3 mph+5.3 mph
70 mph76.2 mph+6.2 mph
80 mph87.1 mph+7.1 mph

Fitting 35x12.50R17 in place of 275/70R17 multiplies every speed and distance reading by 1.08839. Over 10,000 indicated miles the odometer is out by +884 miles.

Effective gearing moves by the same proportion. A vehicle with 3.73 axles running 275/70R17 would need 4.06 to keep the same engine speed on 35x12.50R17. Work it out for your own axle ratio.

Full specification of each size

275/70R17

Derived dimensions for 275/70R17
DimensionMetricImperial
Section width275.0 mm10.83″
Sidewall height192.5 mm7.58″
Wheel diameter431.8 mm17.0″
Overall diameter816.8 mm32.16″
Rolling circumference2,566.1 mm101.03″
Revolutions per mile389.7 / km627.2 / mile
Measuring rim (estimate)216 mm8.5″

35x12.50R17

Derived dimensions for 35x12.50R17
DimensionMetricImperial
Section width317.5 mm12.50″
Sidewall height228.6 mm9.00″
Wheel diameter431.8 mm17.0″
Overall diameter889.0 mm35.00″
Rolling circumference2,792.9 mm109.96″
Revolutions per mile358.1 / km576.2 / mile
Measuring rim (estimate)254 mm10″

Rim widths differ too: 275/70R17 is designed for 8″9.5″ and 35x12.50R17 for 9″11″. Their measuring rims differ, so the same wheel will not be ideal for both.

Can you swap one for the other?

Outside the ±3% rule

The diameter difference of +8.84% exceeds the ±3% rule of thumb. Expect a speedometer error of about 5.3 mph at an indicated 60, and an odometer that is off by the same proportion. It is a common swap even so — it just needs the instruments recalibrated to stay honest.

Neither figure says anything about physical fitment. Whether 35x12.50R17 clears the strut, the fender liner and the steering stops depends on wheel offset and suspension geometry that a size code does not encode. For maintenance rather than sizing, Car Basics covers tire care.

275/70R17 vs 35x12.50R17: common questions

Is 35x12.50R17 bigger than 275/70R17?
35x12.50R17 is 2.84 inches taller and 43 mm wider. In overall diameter that is +8.84%, which exceeds the ±3% rule of thumb for a substitution.
How much will 35x12.50R17 throw off my speedometer?
Every reading scales by 1.08839. An indicated 60 mph becomes 65.3 mph, and every 100 miles on the odometer is really 108.8 miles.
How much does 35x12.50R17 change ground clearance over 275/70R17?
The axle centerline moves by 1.42 inches — half the diameter change, because half the extra height sits below the hub and half above it.
Will 35x12.50R17 fit where 275/70R17 fits?
Nothing derived from the size code can answer that. Clearance depends on wheel offset, suspension travel and body dimensions that no tire size contains. This page tells you exactly what changes dimensionally, which is the part that can be calculated.

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