Remember when 28mm tyres were considered wide? Then 30mm? And the rise of 35mm rubber? Well, hold on to your hats, because Pirelli’s new 40mm road tyre has arrived at BikeRadar HQ.
The 40mm-wide Pirelli P Zero Race TLR is the plumpest option in a range that also includes 26mm, 28mm, 30mm, 32mm and 35mm options.
In terms of width, 40mm is bona fide gravel tyre territory, but the P Zero Race TLR remains a road tyre in its construction and tread pattern – or lack of it.
The tyre uses Pirelli’s 120tpi SpeedCore casing, said to incorporate an inner layer infused with aramid particles to improve the air retention and flexibility of the rubber.
This is combined with the same SmartEvo compound we’ve become familiar with from the Pirelli P Zero Race TLR, a tyre that scored 4.5 stars in our review last year. It’s one of the best road bike tyres we’ve tested, and the fastest tyre we tested in the lab.
How wide is too wide?
What’s the point of a 40mm road tyre? Well, tyre clearances have become increasingly generous on road bikes, with race machines such as the new Giant TCR and new Trek Madone now commonly offering room for 32mm tyres – although, clearly, that’s some way short of this monster from Pirelli.
However, some of the latest endurance bikes can accommodate even wider rubber. The new Specialized Roubaix, for example, has room for 40mm tyres, leaving room for Pirelli’s latest option.
As a result, endurance road bikes are becoming increasingly versatile, treading on the toes of all-road bikes. It gives riders the option to run either gravel tyres for off-road capability, or go super-wide with their road rubber.
At this width, you’re naturally contending with some extra weight – a 40mm P Zero Race TLR comes in at a claimed 460g, compared to a 315g for a 28mm equivalent.
Unless you’re using super-wide rims there will likely be an aerodynamic penalty compared to narrower options too – though, if you’re considering a 40mm road tyre, that’s unlikely to be top of your agenda.
On the upside, we’d expect this to offer a seriously plush ride and fantastic levels of grip.
Road or gravel?
These might also be an interesting option for gravel riders who want a fat-but-fast tyre for dry, smooth conditions, or for those looking to convert their bike into a winter road machine for all-weather riding duties. There’s the comfort of a wide tyre, but there’s also the benefit of maintaining your bike's geometry and ride feel if swapping out a similarly wide gravel tyre.
As tyres have gone increasingly wider, rim widths have broadened, too, and Pirelli says this 40mm P Zero is designed for rims with 21mm internal widths. That’s typical for the latest road and gravel wheels.
In terms of price, you're looking at £74.99 / $94.90 per tyre. There’s no tanwall option; black only.
Is this the first in a new wave of super-wide road tyres? Would you fit a 40mm tyre to your road bike? Does your bike even have the necessary clearance? Let us know in the comments below.
