Tire size comparison
305/45R22 vs 33x12.50R22
33x12.50R22 is +0.6% taller than 305/45R22: 33.0 in vs 32.8 in (+0.19 in), and 0.5 in wider. With 33x12.50R22 on a vehicle set up for 305/45R22, the speedometer shows 60 mph at an actual 60.4 mph. That is within the ±3% difference many shops use as a rule of thumb (not a manufacturer or legal limit).
Set up for: checking a replacement size (33x12.50R22 instead of 305/45R22) · Different situation?
Your current size
e.g. 265/70R17, 2657017 or 33x12.50R20
Where do I find my size?
It's on the tire sidewall, e.g. P265/70R17 115T, and on the tire placard sticker on the driver's door jamb (also in the owner's manual). The placard shows the size the vehicle came with; the sidewall shows what is fitted now. If they differ, use the placard as your starting point. Digits are enough here: 2657017 or 33125020.
Size you're considering
305/45R22 vs 33x12.50R22: full comparison
| 305/45R22 | 33x12.50R22 | Difference | |
|---|---|---|---|
| Overall diameter | 32.81 in | 33.00 in | +0.19 in (+0.6%) |
| Width | 12.01 in | 12.50 in | +0.49 in (+4.1%) |
| Sidewall height | 5.40 in | 5.50 in | +0.10 in |
| Circumference | 103.1 in | 103.7 in | +0.6 in |
| Revs per mile (nominal) | 615 | 611 | −4 |
| Wheel diameter | 22 in | 22 in | ±0 in |
| Diameter in mm | 833 | 838 | +5 mm |
Speedometer difference
Your speedometer is calibrated for 305/45R22. Fitted with 33x12.50R22, the actual speed is the reading × 33.00 ÷ 32.81.
| Speedometer shows | Actual speed | Difference |
|---|---|---|
| 20 mph | 20.1 mph | +0.1 mph |
| 30 mph | 30.2 mph | +0.2 mph |
| 45 mph | 45.3 mph | +0.3 mph |
| 55 mph | 55.3 mph | +0.3 mph |
| 60 mph | 60.4 mph | +0.4 mph |
| 70 mph | 70.4 mph | +0.4 mph |
| 80 mph | 80.5 mph | +0.5 mph |
Real tires: published diameters
305/45R22: 32.7–32.8 in published by 5 makers; 33x12.50R22: 32.5–33 in published by 2 makers. Calculated figures assume a nominal tire; the exact difference between two specific tires depends on their models.
More about each size: 305/45R22 · 33x12.50R22
Related comparisons
FAQ
Which is bigger, 305/45R22 or 33x12.50R22?
33x12.50R22 is +0.6% taller than 305/45R22: 33.0 in vs 32.8 in (+0.19 in).
How much will my speedometer be off with 33x12.50R22 instead of 305/45R22?
The speedometer is calibrated for 305/45R22. With 33x12.50R22 it shows 60 mph when you are doing 60.4 mph, and 70 mph at 70.4 mph (+0.6%). Your speedometer also has its own factory tolerance.
Can I replace 305/45R22 with 33x12.50R22?
The diameter difference is +0.6%. Whether it fits depends on things this calculation can't see: wheel width and offset, clearance at full lock and over bumps, load index and speed rating, and your vehicle maker's approval. Check your door-jamb placard and owner's manual and ask a tire professional.