I recently put 38mm Vittoria Terreno Drys on my 24mm internal width gravel rims. The installed tires actually measure 43.5mm inflated to ~50psi, which is >5mm wider than what’s stated on the tire label. Is this discrepancy between the labelled and installed widths normal?
That seems like more than i would expect but if the tires fit I wouldnt worry about it.
Not knowing how much you and the bike weighs and not if you have tubes or not those tire pressures are probably quite high. You could certainly increase comfort and possibly speed by going lower.
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I actually have a bit of experience with those specific tires. I purchased the Terreno Drys in a 33mm for cyclocross racing which has a strict limit of 33mm tires. I installed them on appropriate CX rims and they measured 35mm even at low pressure (~20psi). They were a few mm’s even wider at high pressures. They were too wide to be legal for CX racing.
That isn’t the same for all tires. Challenge tires in particular are known to be exact for those reasons. But the Vittoria’s are known to be wider then advertised. Not usually a big issue and it probably means you can drop pressure even a little more as Rob suggested 
I have been riding ~38 psi on gravel with 33mm tires which seems pretty good. Although I’ve been tempted to go a little lower for slightly more comfort.
Really happy with the Terreno Dry otherwise. They have fantastic grip when dry, and are actually okay when wet. But they did wear out quite quickly.
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Yes Vittoria specifically seem to inflate wider than their printed number. It may be that Vittoria’s “measuring rim” could be an old-school internal width of like 17 or 18 mm.
@KevinGoertz I know they make all their Terreno tires in 31 mm printed width, so those should stay under the limit on a more modern rim for CX races where you need to fit the gauge.
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Thank you everyone for your input! It’s good to know that the difference is somewhat expected and is not a concern, especially with Vittoria tires.
I’m running them tubeless, they seem to fit well, although they were slowly leaking air at first (with no sealant leaks). After I added some extra sealant, they seem to be holding air much better. I’ll drop the pressure as everyone suggested.
Thank again!
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