Stock vs Replacement Tire Comparator
Compare a replacement tire with the original equipment spec: diameter, width, load index and speed rating checked against the door placard.
Compare replacement dimensions with original specifications.
Stock vs Replacement Tire Comparator: Tire Size Inputs
Compare two tire sizes here. Use the formulas and reference tables below for this tool's specific calculation.
How Stock vs Replacement Tire Comparator Works?
The Stock vs Replacement Tire Comparator works by checking the replacement tire's size, load index and speed rating against the original equipment (OE) values on the door placard. The check runs in 4 steps.
Enter the OE spec
Copy the full size and service description from the placard, for example 215/55 R17 94V.
Enter the replacement
Type the replacement tire's full marking, for example 225/50 R17 94W.
Compare dimensions
The comparator shows diameter, width and sidewall changes in mm, inches and percent.
Compare ratings
The comparator confirms the load index is equal or higher and the speed rating is equal or higher than OE.
Stock vs Replacement Tire Comparator Formula
The Stock vs Replacement Tire Comparator passes a tire when |Δ%OD| ≤ 3, LI_rep ≥ LI_OE and SR_rep ≥ SR_OE.
|OD_rep − OD_OE| ÷ OD_OE × 100 ≤ 3Capacity(LI_rep) ≥ Capacity(LI_OE)Speed(SR_rep) ≥ Speed(SR_OE)- OE
- Original equipment specification
- LI
- Load index
- SR
- Speed rating letter
Worked example
An OE 215/55 R17 94V tire carries 670 kg (1,477 lb) at up to 240 km/h (149 mph). A 205/60 R17 93H replacement is 1.42% taller but carries 650 kg (1,433 lb) at 210 km/h (130 mph), so the replacement falls below OE on load and speed.
Stock vs Replacement Tire Comparator Conversion Table
The Stock vs Replacement Tire Comparator conversion table checks 6 replacement tires against a 215/55 R17 94V original equipment spec.
| Replacement | Diameter gap | Load capacity | Speed rating | Result |
|---|---|---|---|---|
| 215/55 R17 94V | +0.00% | 670 kg (1,477 lb) | V | Meets OE |
| 215/55 R17 98W | +0.00% | 750 kg (1,653 lb) | W | Meets OE |
| 225/50 R17 94W | -1.72% | 670 kg (1,477 lb) | W | Meets OE |
| 205/60 R17 93H | +1.42% | 650 kg (1,433 lb) | H | Below OE |
| 225/55 R17 97V | +1.65% | 730 kg (1,609 lb) | V | Meets OE |
| 215/60 R17 96H | +3.22% | 710 kg (1,565 lb) | H | Below OE |
What is Stock vs Replacement Tire Comparator?
A Stock vs Replacement Tire Comparator is a tool that checks a replacement tire against the vehicle maker's original tire specification on size, load and speed. The door placard or owner's manual lists the original specification.
A replacement tire passes when the diameter stays close to OE and the load index and speed rating match or exceed OE. A lower rating reduces the tire's safety margin and can void insurance cover in some markets.
The comparator combines a size check and a rating check in one result.
What are the uses of Stock vs Replacement Tire Comparator?
There are 4 main uses of the Stock vs Replacement Tire Comparator, including quote checking and used car inspections.
Quote checking
Confirm a shop's quoted tire meets the placard spec.
Used car inspections
Check that tires on a used car match OE ratings.
Budget tires
Confirm a lower-cost tire does not drop below OE load or speed.
Insurance records
Record that replacement tires meet the maker's spec.
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