What does 103V mean on a tire?
| Load per tire875 kg — index 103 on the ISO scale | 1,929lb |
|---|---|
| All four tiresthe ceiling for vehicle plus everything in it, not a target | 7,716lb |
| Speed rating V240 km/h — sports cars and performance sedans | 149mph |
| Next index up (104)55 lb more per tire | 1,984lb |
| Next index down (102)55 lb less per tire — do not fit this if your door label says 103 | 1,874lb |
Notes
- 103V means two separate things. 103 is the load index: this tire carries 1,929 lb on its own, at the pressure printed on the sidewall. V is the speed rating: the tire is built to hold together at 149 mph. The two numbers are unrelated — a high load index says nothing about speed, and vice versa.
- The load figure is per tire, not per vehicle. Four 103-rated tires carry 7,716 lb between them, and that has to cover the car, the fuel, the passengers and whatever is in the boot. Compare it against the gross vehicle weight rating on the door jamb, not against the kerb weight in the brochure.
- Never fit a lower index than the door label. The placard inside the driver's door gives the minimum load index the manufacturer signed off on. Going below it is the one substitution in tire fitment that has no upside — it saves a few dollars and removes margin from the only four patches of rubber holding the car down.
- A speed rating is a ceiling, not a recommendation. V at 149 mph assumes correct pressure, correct load and a tire in good condition. Under-inflation is what actually destroys tires at speed, and it does it well below the rated number.
- Both markings sit at the end of the size, after the diameter: a tire marked 225/45R17 103V is a 225-wide, 45-series, 17-inch tire rated 1,929 lb and 149 mph.
103V is two answers, not one
103 is the load index: this tire carries 1,929 lb on its own. V is the speed rating: the tire is built to hold together at 149 mph.
The two are unrelated. A high load index says nothing about speed, and a fast tire is not automatically a strong one.
The load figure is per tire
Four 103-rated tires carry 7,716 lb between them — and that has to cover the car, the fuel, the passengers and everything in the boot.
Compare it against the gross vehicle weight rating on the door jamb, not the kerb weight in the brochure. The two numbers differ by several hundred pounds on most cars, and the brochure is the one that flatters.
Never fit a lower index than the door label
The placard inside the driver's door gives the minimum load index the manufacturer signed off on.
Going below it is the one substitution in tire fitment with no upside: it saves a few dollars and takes margin out of the only four patches of rubber holding the car on the road.
A speed rating is a ceiling, not a recommendation
V = 149 mph (240 km/h) assumes correct pressure, correct load and a tire in good condition.
Under-inflation is what actually destroys tires at speed, and it does it well below the rated number.
Where to find it on the sidewall
Both markings sit at the end of the size, after the diameter — a tire marked 225/45R17 103V is a 225-wide, 45-series, 17-inch tire rated 1,929 lb and 149 mph.
Nearby sizes
Read more
- Load Index and Speed Rating — The Two Codes at the End of the SizeEveryone reads the size and stops. The two characters after it are the ones with a safety consequence.
- Speedometer Error From Tire Size — One Ratio, and It Runs Both WaysA one-inch increase in diameter on a 30-inch tire is a 3.3% error. At an indicated 70 you are doing a bit over 72.
- Recalibrating a Speedometer After a Tire Change: Four Routes, and How to Verify It WorkedOn most modern vehicles the tire size is a stored number, not a mechanical ratio. Where that is true, correcting it takes minutes; where it is not, the options get physical.
- Plus Sizing Chart: Wider Tire, Shorter Sidewall, Same Rolling DiameterPlus sizing trades sidewall for wheel and keeps the overall diameter where it was. Done properly nothing on the vehicle notices — which is the entire point.