Scoring a perfect 10, the Hillbilly GRID Gravity T9 is an impressive choice for terrain that's tough on tyres

Product Overview

Overall rating:

Score 10

Specialized Hillbilly GRID Gravity T9


  • The excellent price, Works great on slimy roots and rocks as well as loose mud, Fine in drier conditions too, Tough and durable.


  • One of the heaviest DH/Enduro mud tyres around, Slower rolling than some similar tyres.


Specialized Hillbilly GRID Gravity T9 tyre review


Price as reviewed:


Specialized’s Hillbilly was the original cut down mud spike inspired by DH champ Sam Hill’s mechanic, and brought to market over a decade ago. It used to be made by CST/Maxxis and has been through several versions, to arrive at the point today where Spesh uses its own factory and proprietary rubber compounds and treads.

This version uses the Gravity casing, which means double ply layers for DH-level protection and toughness, and T9 rubber, which is the brand’s softest, stickiest and slowest-rebounding formula. There’s also a £5 cheaper, lighter-weight Trail-casing Hillbilly with one less ply layer, and both versions come in 29in and 27.5in sizes.

Making its own MTB tyres from scratch has taken Spesh a few years to perfect, but don’t confuse the latest-generation tyres with previous Gripton versions. Like this Hillbilly with an all-new tread pattern, they’re all now much improved, with great rubber and casings, while still remaining excellent value.

While following the common mud tyre pattern of a moto-style, spaced-out, blocky tread for good penetration and mud clearing, zoom in on the latest Hillbilly tread and there’s more going on. Each shoulder block alternates and is slightly angled outwards (like a less pronounced Magic Mary) and within every other knob is a weird little raised tread block with a heavy siped panel. This uses micro-sized rubber fins (a bit like a file tread), presumably to better splay out and connect to roots and rocks. There is also a similar ribbed tread on the outside of the alternate shoulder blocks, as well as more lateral siping on the broadly spaced out alternate central paddles. 

Specialized Hillbilly GRID Gravity T9 tyre

Combine this detailed tread with Specialized’s slurpiest T9 rubber and there’s a hell of a lot of friction and grip on little edges, shiny roots and rocks, as well as great bite into loose soils and good mud shedding from the spaced-out pattern.

I was pretty amazed by the Hillbilly’s performance on a day riding in melted snow, and how well it dealt with really mushy ground where you couldn’t see much under leaves and slush.

It never felt pingy or nervous, even hitting polished roots or slotting through eroded ruts and, overall, the new tread has superb grip and tracking without ever oversteering or pulling in muddy ruts. The really well-damped casing and tread blocks resist excessive bouncing and deflection off hard edges, and the Hillbilly even works reasonably well on polished bike park type surfaces – somewhere most mud tyres struggle.

All this grip does come with a rolling resistance penalty, but it’s not as crippling as something like Michelin’s Wild Mud. At 1,360g, it is at the top end of acceptable for an enduro bike, and you clearly know you’re lugging a big chunk around when pedalling uphill, so I’d likely opt for the Trail casing, unless you live somewhere really tough on tyres, or are sticking one on an e-bike.


This Hillbilly is great then, but is it better than its direct rival, the latest Maxxis Shorty? Overall grip is definitely on a par, and actually even marginally better in some scenarios, but the Hillbilly is slightly slower rolling and heavier in the equivalent DH casing version. The Shorty is slightly more versatile, rolling with more pace on harder trail centre-style surfaces, and it’s arguably more optimised to mixed conditions than the very open, slightly spikier, Spesh tread. So horses for courses then, meaning this Hillbilly totally deserves top marks too, particularly as it’s £30 cheaper than the Shorty.


Weight:1,360g (29 x 2.4in)
Sizes:27.5 & 29x2.4in
Casings:GRID Trail and GRID Gravity