Introduction

The standard fitment tires supplied on Range Rovers fall into the category of mild "All-Terrain" tires. This family of tire, whatever the brand, is designed as a compromise between pavement and off road ability, usually more biased towards the former. In my opinion, the stock tires supplied on Range Rovers are as good as or better than most all-terrain designs when it comes to off-road performance, and are also better on the pavement. Range Rover tires are rated for higher speeds than other 4X4 tires -- a factor to consider when swapping to non-stock rubber. Classics came with "S" rated tires, while the 4.0/4.6 models come with "H" rated rubber. (Photo: Michelin XMS244 modified by author's driving)

All-Terrain versus Mud-Terrain Tires

Overview:
Nowadays, so-called "All-Terrain" (AT) tires are so similar to street tires that there is little off-road advantage to be gained by some of them. The latest re-design of the BFG A/T is a welcome exception to this rule, with wider voids at the shoulders. Also slightly more aggressive average are the recently introduced Big O XT, and Cooper Discoverer ST. These have tread patterns with larger voids than traditional all-terrains, and are uniformly open across the tire surface. They look more aggressive, and are noisier, but the tread blocks are larger as well as the voids, and I am not sure how much advantage is gained overall. 

For serious off road use, however, the principal alternative tread design to an All-Terrain (AT)  is the Mud-Terrain (MT) tire -- aggressive, no-nonsense treads designed to perform well in mud, but with drawbacks in highway noise, grip, and responsiveness. Mud tires are poor performers on wet pavement, ice and snow, and care must be taken in sand not to let them dig you in. But, mud is where you tend to get stuck, and mud tires are almost the only answer there. (I say almost, because  some people advocate using chains instead).

Comparisons:
Bob Watson did a back-to-back comparison of the BF Goodrich M/T tires vs. A/T's otf the same brand mounted on his '95 Discovery, around a muddy course of varying texture and depth. The M/T had excellent self-cleaning and grip, with little tire spin, making the course a cake walk. There was a good feeling of grip and control even in the slimy stuff. The A/T gave more tire spin, slipping and sliding, and required a slightly different technique to compensate for the lower traction, but was adequate. Overall,  he thought the M/T's are great for the muddy trail and the A/T's are great everywhere else and still good enough for those spur of the moment trail runs. Bob felt his mud- oriented Cooper STTs gripped less well than BFG MTs and were slippery on wet pavement. He now uses special BFG MT's with the 2 center rows of lugs siped at Discount Tire. The siping helps wet, ice and snow grip, but leaves the outer lugs solid to avoid tearing on rocks etc.

Jeff Kessler found that switching his 1988 Range Rover to BF Goodrich A/Ts made him appreciate the pavement handling of the OEM Michelins, which by comparison felt like being on rails.  On a Rovers North off-road course, greasy mud packed up the A/Ts solid, but he felt better after seeing the same on the M/Ts on a  94 D90 parked next to him.

I have found the user-generated reviews and ratings posted at The Tire Rack fairly helpful in comparing the different classes and brands of tire, based on the ownher's usage patterns (mostly off road, on/off road, mostly on-road etc).

Handling and Tracking Differences:
I have heard several cases of people reporting tracking problems with mud tires on Classic Range Rovers. The Classic takes some attention to keep it on course on the freeway at the best of times, but with mud tires this characteristic seems to be exacerbated. Gordon Kallio uses BFG M/Ts (245/75R16) seasonally on his 92 Classic, and has been unable to get them to track straight and true. Brett Gottdener uses BFG MTs (225/75R16) on his LWB, and notices that freeway driving is now more difficult, with the car now needing constant input through the steering wheel to keep in the lane. Understeer is more pronounced and oversteer happens more easily, but none of this is scary or dramatic. In mud, however, he felt the difference was totally worth it -- the Michelins would just spin, but there wasn't even the slightest loss of traction. He also reports a softer ride than stock. He did not notice a large increase in noise, but feels this may be obscured by his lights and rack on top.

Really Serious Mud Tires:
The usual M/T tires mentioned above are fairly mild compared to the really serious mud tires used by the military and by mud boggers. Phil Martin, from Guernsey in the Channel Islands, used Michelin XCLs (as used on Camel Trophy vehicles for years) in the 650-16 size on his 84 Range Rover 4-door. This tyre has now been superseded by the Michelin 4x4 XZL which he uses in 700x16 size, for off road/field work. It is not as noisy on the road as XCL's, but is a bit "skittish" on damp roads due to its construction. This only happens at speed, so he drives conservatively on recently damp roads. Interco Super Swampers and the Mickey Thompson Baja Claws pictured on Bruce Lawrence's 4.6 RR are other examples of the "beyond M/T" category. With these tires the mud performance is usually even better than with conventional M/Ts, but the penalties in other conditions (especially wet or icy pavement) are correspondingly greater.

Commercial Traction Tires

A middle ground between AT and MT tread designs is traditionally found in Commercial Ultra Traction tires. These were designed for true all-round performance in mud, ice and snow as well as pavement for demanding commercial users. They are becoming increasingly popular with 4X4 owners as so-called "All Terrain" designs become more pavement oriented, and the manufacturers are accordingly starting to market them to us. They generally use an all-season/all-terrain pattern in the center (with closely spaced, siped tread blocks for good performance on wet and dry pavement, ice and snow), and open mud-terrain type lugs on the outside for real mud traction. They are also pinned for studs. Users report much improved mud performance at a slight penalty in pavement performance and noise.

Examples in order of increasing aggressiveness are the Dunlop Radial Rover R/T, the BF Goodrich Trac-Edge, and the Cooper Discoverer CTD.  (Photo: Cooper Discoverer CTD, 245/75R16 on Range Rover 4.0SE). Unfortunately only the Dunlop RT is still available in the US, although the Trac Edge continues to be sold in the UK market.  

The Dunlop R/T, for example, gives no significant difference in noise compared with the Michelin XMS 244, is pinned for studs, works well in snow, is inexpensive and readily available (for example The Tire Rack sells it for about $96 for the 225/75R16 size most Rover owners use). Bear in mind, however, that these tires are designed for the wear and tear of commercial use, with rubber compounds formulated for long tread life on gravel rather than maximum pavement grip. Like many mud-terrains, they are rated for heavier loads (load range D and E rather than the C of the standard fitment Michelins), so may give a slightly harder ride than stock.

I have used both Dunlop RTs and Cooper CTDs with excellent results. Dale Avery has used his CTDs in sand, gravel, snow, ice, and rocky (not boulder) conditions and likes them a lot.  At a recent off-road training course, the lead instructor was very impressed with them after Dale drove up a very steep sand bank without any problems.

Noise Rankings Vs Traction Rankings:
I found the Dunlop RTs to be very quiet (nearly as quiet as the stockers) although they got slightly noisier with age. I found the CTDs noisier than the Dunlops, but not enough to be intrusive. Granville Pool found the Trac Edges to be very noisy, intruding even above the wind noise caused by his tall roof rack at high speed. My ranking of these commercial traction tires from quietest to noisiest would be: Dunlop RT, Big O XT, Cooper CTD, BFG Trac Edge. Of course, the ranking in terms of traction and effectiveness off road would be almost exactly the opposite! (although I might rate the Dunlop RT slightly higher in this regard than the Big O XT). For more complete noise and comfort rankings of the various brands, see the user-supplied ratings at The Tire Rack.

Please email me if you have experience with non-standard tires and/or wheels.