What is the acceptable tire size difference?

Most industry professionals recommend staying within a 3% difference in overall diameter from the original factory tire size to maintain brake clearance, suspension travel, and ABS/traction control accuracy.

What happens if tire size difference is too big?

Exceeding a 3% difference can cause tires to rub against wheel wells, trigger ABS system faults, alter transmission shift points, and cause inaccurate speedometer readings.

Is it OK to have a 1 inch difference in tire size?

On a large truck tire (like a 33-inch tire), a 1-inch difference is about 3% and usually acceptable. On a small compact car tire (like a 24-inch tire), a 1-inch difference is over 4% and could cause clearance issues.

How do I check AWD tire size difference?

AWD systems are extremely sensitive. All four tires must typically be the exact same size, brand, and tread depth. Subaru, for example, requires all tires to be within 1/4-inch of rolling circumference of each other.

What is the difference between 265 and 275 tires?

A 275 tire is exactly 10 millimeters (about 0.39 inches) wider than a 265 tire. If the aspect ratio and rim size are the same, the 275 tire will also be slightly taller.

Tire Size Difference Calculator

Calculate the percentage difference between two tire sizes to ensure safe suspension and drivetrain fitment.

Quick Answer

When switching from a factory 265/70R17 to a 285/70R17, the size difference is an increase of 3.4% in overall diameter (from 31.6" to 32.7"). This falls just outside the standard 3% safety recommendation, meaning suspension clearance should be checked before installation.

Enter Tire Specifications

① Original Tire

Width (mm)

Aspect Ratio (%)

Rim (in)

→ 265/70R17

② Compare Tire

Width (mm)

Aspect Ratio (%)

Rim (in)

→ 285/70R17

Enter tire specs above and click Calculate to compare

Supports P-metric (225/65R17) and Imperial/flotation (31x10.5R15) formats

Size Difference Between Common Plus-Size Swaps

Factory Size	Plus Size	Diameter Diff (in)	Diameter Diff (%)	Verdict
225/65R17	235/65R17	+0.51"	+1.79%	Safe
245/75R16	265/75R16	+1.18"	+3.87%	Borderline
265/70R17	285/70R17	+1.10"	+3.48%	Borderline
275/55R20	275/60R20	+1.08"	+3.38%	Borderline
205/55R16	225/50R16	-0.04"	-0.16%	Safe
235/45R17	245/40R17	-0.61"	-2.40%	Safe

Formula

Diameter Difference % = |Old Diameter − New Diameter| / Old Diameter × 100

Old Diameter = original factory tire overall height in inches
New Diameter = replacement tire overall height in inches
Example: |31.61 − 32.71| / 31.61 × 100 = 3.48% (borderline)

Frequently Asked Questions

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