Low Rolling Resistance Tires: Worth It for Hybrids?

You bought a hybrid to save fuel. Do the tires matter?

Hybrid owners notice small changes in mpg, so the question comes up at every tire change: should the new set be "low rolling resistance" (LRR)? The short answer is that it helps a little, pressure helps about as much, and grip in the rain should come first. Here's the evidence for each part.

What rolling resistance is

Rolling resistance is the energy a tire uses up just by rolling: the rubber flexes as it meets the road and recovers as it leaves, and some of that energy turns into heat. Every bit of it has to come from the engine or the battery.

Tire makers lower it with tread compounds, construction and tread design. Michelin, for example, says tires made for electric cars are designed with low rolling resistance in mind to help range.

How much fuel it saves

NHTSA tested this directly while building its tire fuel efficiency program. In report DOT HS 811 154, tires of 15 different models with known rolling resistance were fitted to the same car. A 10% decrease in rolling resistance gave about a 1.1% increase in fuel economy.

So LRR tires save fuel, but in small steps. What that means for your car depends on:

• Which two tires you're comparing. The gap between the most and least efficient tire in a size can be large or small.
• How you drive. Speed, loads and the mix of highway and city miles all change the result.
• How long you keep the set. Small savings add up over tens of thousands of miles.

Do the math for your own car

The 1.1% figure is easiest to judge in your own numbers. As a worked example, a hybrid averaging 50 mpg would gain a little over half an mpg from tires with 10% lower rolling resistance. A car averaging 30 mpg would gain about a third of an mpg. Over a set's life that adds up to real fuel, but it's not a reason to accept a tire that brakes worse in the rain.

Two questions make the comparison fairer:

• Compared with what? "Low rolling resistance" is a description, not a rating with a fixed threshold. Ask how the tire compares with the one you have now, not with an average.
• For how long? Wet grip changes as a tire wears. A tire that's efficient and grippy when new still needs replacing at 4/32.

Hybrid-specific checks

Hybrids carry a battery pack, and some are heavier than the gas version of the same model. That makes two things worth a second look:

• Load index. Use the number on the door placard as the floor. If the original tires were XL (extra load), the replacements should be too. Our load index guide explains the chart.
• Noise. Hybrids run quietly at low speed, so tire noise is easier to hear. If quiet matters to you, weigh it alongside efficiency.

The free version: pressure

Before you pay extra for efficiency, make sure you're not giving it away. Fueleconomy.gov says keeping tires at the correct pressure improves gas mileage by 0.6% on average, and up to 3% in some cases. Under-inflated tires can lower mileage by about 0.2% for every 1 psi drop in the average pressure of all four tires.

Two notes from the same page: use the pressure on the sticker in the door jamb or in your owner's manual, and don't use the maximum pressure printed on the sidewall. Our sidewall max PSI post explains why.

A tire that's low by a few psi can cancel out much of what a more efficient tire would save. Check cold, monthly. Our pressure guide shows how.

The trade-off to watch: wet grip

Tire makers balance three things against each other: rolling resistance, grip and tread life. Push one hard and the others can move. That's why Consumer Reports' advice is to look first for a tire with good braking, handling and hydroplaning resistance, and then use rolling resistance as a tie-breaker.

In South Florida, that order matters. Our rainy season brings heavy afternoon storms for months, and hydroplaning is the risk that costs more than any fuel bill. When you compare tires:

1. Match the size, load index and speed rating your vehicle maker specifies. That's first, always.
2. Check wet braking. The UTQG traction grade (AA, A, B or C) is a starting point for straight-line wet braking. Try the explainer below.
3. Look at independent test results for hydroplaning and handling where you can find them.
4. Then compare rolling resistance among the tires that pass the first three.

Our UTQG guide explains all three grades.

Tread depth matters more than the label

An efficient tire on worn tread is still a worn tire. AAA's testing found tires worn to 4/32 of an inch took an average of 87 feet longer to stop on wet pavement than new tires, and AAA recommends replacing at 4/32. Our post on why 4/32 matters in Florida rain has the details.

Hybrid vs EV: what's different

Hybrids and EVs both care about efficiency, but EVs add weight and instant torque, which wear tires faster. If you drive a plug-in or full EV, read our post on EV tire wear and budgeting and our EV tires guide too. For a conventional hybrid, the steps above are the whole story.

Where not to economize

• Load index. Never below the original, whatever the efficiency rating.
• Wet grip. A fraction of an mpg isn't worth a weaker wet-braking tire in our climate.
• Matching. Replace in sets or pairs as your manual asks, so an axle doesn't run two different tires.

The hybrid tire checklist

Ready to look? Compare tires side by side on our compare page, or shop by size. Shipping is free to the 48 contiguous states and DC. In Miami-Dade, Broward and Palm Beach we install at our Sunrise shop or by mobile van.