The cheapest truck tire on the quote is rarely the cheapest tire on the road. A tire that costs 25% more but runs 40% longer has a lower truck tire cost per km. That figure, CPK, is the fairest way to compare tires before you buy.
I have spent years helping fleets and dealers compare tires, and cost per kilometer is the first number I ask for. It is simple, fair and hard to argue with. In this guide I show how I calculate it, where it can mislead you, and how I use it before signing a purchase order.
What is tire CPK?
CPK is the tire price divided by the distance it is expected to run:
CPK = tire price ÷ expected mileage (km)
A lower CPK means the tire costs less to run per kilometer. Fuel, installation, maintenance and taxes are not included unless you add them to the price.
A worked example (illustrative numbers)
Your fleet runs a drive tire at 420 USD that you expect to last 90,000 km. A supplier offers a premium tire at 520 USD that should last 125,000 km.
| Current tire | Proposed tire | |
|---|---|---|
| Price (USD) | 420 | 520 |
| Expected mileage (km) | 90,000 | 125,000 |
| CPK (USD per 1,000 km) | 4.67 | 4.16 |
The proposed tire costs 100 USD more but is about 11% cheaper per kilometer. The premium only wins if the mileage claim is realistic, so ask the supplier for evidence and compare it with your own wear records.
The break-even price
Sales teams often ask the opposite question: how much can the new tire cost and still match the current one? Multiply the current CPK by the new tire’s mileage:
equivalent price = current CPK × proposed tire mileage
Here that is 0.004667 × 125,000 = about 583 USD. Any price below that beats your current tire on cost per kilometer. This is the equivalent competitive price the calculator reports.
Why mileage is the number to challenge
CPK is only as good as the mileage you enter. Load, tire pressure, wheel alignment, road conditions, driving behavior and maintenance all move the result. Track actual wear so next year’s estimate rests on your own data. The Tire Performance tool turns measured tread depth into km per mm, and our Wheel Alignment tool shows what poor alignment can cost.
Try it with your own tires
Enter both tires’ price and expected mileage in the Tire CPK Equalizer. It supports many currencies and exports a PDF report you can send to a buyer or a customer.
Why I Start With Cost Per Km
When a supplier quotes two tires, the price is the number everybody sees first. But a tire is bought to deliver kilometers, not to sit on a shelf. CPK converts the price into the thing you actually consume. It lets you compare a cheap tire and a premium tire on the same scale, and it lets the buyer, the workshop and the owner discuss one figure. In my experience, simply asking “how many kilometers will this tire deliver on my axle?” changes the conversation with a supplier.
How I Calculate CPK Step by Step
- Pick one axle position. Steer, drive and trailer tires wear differently, so never mix them in one comparison.
- Collect the full price. Include the tire, valve, balancing and fitting if they differ between options.
- Estimate mileage from your own records. Use kilometers you have seen on similar vehicles and routes, not a brochure figure.
- Divide price by mileage. I express the result per 1,000 km, because small decimals are easy to misread.
- Compare with the tire you use today. The difference tells you whether the new option is worth testing.
Adding Casing Value and Retreads
The basic formula ignores what is left when the tread is gone. A casing in good condition can be sold or retreaded, and that value belongs in the calculation. A more complete version is:
net CPK = (tire price − expected casing value) ÷ expected mileage
Using the illustrative numbers from the example above, if the 520 USD tire leaves a casing worth 100 USD, the net cost is 420 USD over 125,000 km, or about 3.36 USD per 1,000 km. If instead you retread the casing for 200 USD and it delivers a further 80,000 km, the combined cost is 720 USD over 205,000 km, or about 3.51 USD per 1,000 km. These figures are only assumptions to show the method, but they show why a strong casing is worth paying for.
What CPK Does Not Tell You
CPK is a purchasing tool, not the whole story. I always remind fleet managers that a low CPK can hide other costs:
- Fuel use. Two tires with the same CPK can burn different amounts of fuel, because rolling resistance differs between designs.
- Downtime. A tire that fails on the road costs far more than its price, once you add the recovery, the delay and the idle truck.
- Safety and handling. Wet grip and braking performance never appear in a CPK figure.
- Misalignment and pressure problems. These reduce mileage on any tire, which is why we explain the effect in our guide to wheel alignment savings.
Mistakes I See When Fleets Compare Tires
- Using the manufacturer’s best-case mileage for one tire and a conservative figure for another.
- Comparing a steer tire with a drive or trailer tire.
- Ignoring casing value, which makes premium tires look more expensive than they are.
- Forgetting that the mileage estimate depends on load, pressure and alignment.
- Changing several things at once, such as brand, size and axle position, so the result cannot be explained.
Getting Reliable Mileage Numbers
The weakest part of any CPK calculation is the mileage. The only way to make it reliable is to measure. Record the odometer reading when a tire is fitted, measure the tread depth at the same positions at every service, and note the reason for removal. After a few months you can calculate the wear rate in kilometers per millimeter and project the total life with much more confidence. The Tire Performance tool does this calculation for you.
Make sure you separate tires by position and by vehicle type. A tire on a regional delivery truck and a tire on a long-haul tractor will not give the same kilometers, even on the same brand and size.
Using CPK When You Negotiate
CPK is also a practical negotiation tool. When a supplier offers a premium tire, ask them to state the expected mileage in writing for your application. Then use the break-even price formula to see how much you can pay and still come out ahead. If you are unsure about the claim, ask for a trial on a small number of vehicles and agree in advance how the results will be measured. A supplier who is confident in the product will usually welcome that.
Finally, check the warranty and adjustment policy. A tire that carries a clear mileage adjustment gives you some protection if the result falls short of the promise.
A Quick Checklist Before You Buy
- Confirm the axle position and service the tire is designed for.
- Ask for the expected mileage for your application, in writing.
- Calculate CPK and net CPK with casing value included.
- Compare the result with your own wear records for the tire you use today.
- Check wet grip, fuel efficiency and warranty terms alongside the price.
- Start with a small trial before you change the whole fleet.
How Often I Review CPK
I recommend reviewing CPK at least twice a year, and whenever you change tire brand, route type or maintenance practice. Fuel prices, tire prices and operating conditions all move, so a comparison that was correct last year may not be correct today. Keep the records simple, update them after each tire removal and let the data show you which tires truly earn their place in your fleet. You can run each comparison yourself in the Tire CPK Equalizer.
My Final Advice
Do not let a single number make the decision for you. Use CPK to narrow the choices, then confirm with a trial on your own vehicles, and keep recording the results. Over time your own records become more valuable than any quote, and they give you real leverage when you negotiate.
FAQ
What does CPK mean for truck tires?
CPK means cost per kilometer: the tire price divided by the kilometers it is expected to run.
Does a cheaper tire always cost less to run?
No. A higher-priced tire can have a lower CPK if it lasts long enough. Compare CPK, not price.
Can I compare tires of different brands?
Yes, if they are for the same axle position and service, and the expected mileage for each is realistic.
