Why Lab
Results And
Road Results
Disagree

Rolling resistance has two components. The first is casing deformation loss — the tiny amount of energy lost every time the tyre's casing flexes as it rolls, which a smooth steel drum measures very well. On that test alone, a narrower tyre run at higher pressure genuinely does show lower losses, because there's less rubber flexing per rotation.

The second component is vibration loss, and a perfectly smooth drum cannot produce it at all. Real tarmac has texture — small cracks, chip-seal grain, patched sections — and every one of those bumps either gets absorbed by the tyre deforming around it, or transmitted straight up through the frame into the rider as vibration. That transmitted vibration is wasted energy, exactly as real as the energy lost to casing flex, and a narrow tyre at high pressure is worse at absorbing it, not better.

SILCA's on-road testing (see sources below) found that once you add real-road texture back into the equation, a wider tyre run at its own correctly lower pressure loses less total energy than a narrower tyre at higher pressure — even though the narrower tyre still wins on a smooth drum. Indian road surfaces, with far more patch-and-crack texture than a European test track, push this result even further in the wider tyre's favour.

How To
Actually Pick
The Right
Tyre

Width isn't a single "faster" number you can look up — it's a decision that depends on your rim, your surface, and what you're optimising for:

1. Check your rim's internal width first. A tyre mounted on a rim that's too narrow for it bulges into a lightbulb shape instead of sitting flush with the rim's sidewall — that mismatch hurts aerodynamics and can compromise the tyre's structure regardless of what width is printed on the sidewall. Match the tyre to what your specific rim is designed for before anything else.
2. 25mm still has a real case — on genuinely smooth tarmac, at speed, with a rider chasing every last watt on race day. If you're racing on closed, well-maintained circuits, the lab result isn't wrong for that specific surface.
3. 28mm (and wider, on gravel or badly broken tarmac) is the better default for everyday Indian riding. Broken tarmac, patched monsoon damage, unswept debris at the road edge — this is exactly the texture that flips the rolling-resistance result, on top of the extra comfort and puncture margin a wider casing gives you for free.
4. Confirm your frame and brake caliper actually clear the width you want. Going from 25mm to 28mm (or wider) needs enough clearance at the chainstays, seatstays, and brake arms — check this before buying, not after the tyre won't sit in the frame.

Getting Your
Pressure
Actually
Right

Tyre width and tyre pressure are the same decision, not two separate ones — a wider tyre run at the wrong (too-high) pressure throws away the exact advantage it's supposed to give you. As a starting point rather than gospel:

1. Start from a baseline and adjust for weight. A rough anchor point: a rider-plus-bike system weight of about 75kg runs roughly 65 psi front / 70 psi rear on a 30mm tubeless tyre. Add or subtract about 0.7 psi for every kilogram your system weight sits above or below that.
2. Adjust for width. For roughly every 2mm you go wider than that 30mm reference, drop about 8 psi; for every 2mm narrower, add about 8 psi. Moving from 30mm down to 25mm, for example, pushes you meaningfully higher than that baseline.
3. Run the rear a few psi higher than the front. Most of your weight sits over the rear wheel, so the rear tyre typically wants 5-7 psi more than the front to deform by a similar amount.
4. Tubeless gets to run lower than tubed. Without an inner tube's own resistance to flex, a tubeless setup can typically run 5-10 psi lower than the same tyre with a tube in it, for the same feel and pinch-flat margin.
5. Treat any formula as a starting point, not a final answer. Rim width, tyre casing stiffness, and riding surface all shift the right number — a dedicated calculator from a tyre manufacturer (Silca, Vittoria, and similar all publish free ones) will get you closer than any single formula, this one included.