Tire size comparison
285/50R22 vs 305/45R22
305/45R22 is −1.2% shorter than 285/50R22: 32.8 in vs 33.2 in (−0.41 in), and 0.8 in wider. With 305/45R22 on a vehicle set up for 285/50R22, the speedometer shows 60 mph at an actual 59.3 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 (305/45R22 instead of 285/50R22) · 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
285/50R22 vs 305/45R22: full comparison
| 285/50R22 | 305/45R22 | Difference | |
|---|---|---|---|
| Overall diameter | 33.22 in | 32.81 in | −0.41 in (−1.2%) |
| Width | 11.22 in | 12.01 in | +0.79 in (+7.0%) |
| Sidewall height | 5.61 in | 5.40 in | −0.21 in |
| Circumference | 104.4 in | 103.1 in | −1.3 in |
| Revs per mile (nominal) | 607 | 615 | +8 |
| Wheel diameter | 22 in | 22 in | ±0 in |
| Diameter in mm | 844 | 833 | −10 mm |
Speedometer difference
Your speedometer is calibrated for 285/50R22. Fitted with 305/45R22, the actual speed is the reading × 32.81 ÷ 33.22.
| Speedometer shows | Actual speed | Difference |
|---|---|---|
| 20 mph | 19.8 mph | −0.2 mph |
| 30 mph | 29.6 mph | −0.4 mph |
| 45 mph | 44.4 mph | −0.6 mph |
| 55 mph | 54.3 mph | −0.7 mph |
| 60 mph | 59.3 mph | −0.7 mph |
| 70 mph | 69.1 mph | −0.9 mph |
| 80 mph | 79.0 mph | −1.0 mph |
Real tires: published diameters
285/50R22: 33.27–33.5 in published by 2 makers; 305/45R22: 32.7–32.8 in published by 5 makers. Calculated figures assume a nominal tire; the exact difference between two specific tires depends on their models.
More about each size: 285/50R22 · 305/45R22
Related comparisons
FAQ
Which is bigger, 285/50R22 or 305/45R22?
305/45R22 is −1.2% shorter than 285/50R22: 32.8 in vs 33.2 in (−0.41 in).
How much will my speedometer be off with 305/45R22 instead of 285/50R22?
The speedometer is calibrated for 285/50R22. With 305/45R22 it shows 60 mph when you are doing 59.3 mph, and 70 mph at 69.1 mph (−1.2%). Your speedometer also has its own factory tolerance.
Can I replace 285/50R22 with 305/45R22?
The diameter difference is −1.2%. 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.