A set of sticky tyres is probably the most cost-effective
performance mod you can make to your 4x4. Tread patterns
offer varying degrees of performance in different terrains,
larger tyres increase clearance,
broader tyres may or may not offer better floatation, etc.
Here is the concept of the "whole 4x4". You want your tyres
to work with everything else. How much articulation, ride
quality or safety do you sacrifice when you change tread
pattern or fit really huge tyres? I've recounted some of
my own experiences below, hoping it will make your decision
easier. I've also included links to a
tyre glossary, as well as a
page describing what you'll see on metric, floatation and
numeric tyre sidewalls.
I drive a Jeep Wrangler TJ which takes me to work every day, but also
does a fair amount of weekend off-roading, and about 6 trails a year.
For starters, the Jeep came with Goodyear Wrangler GS-A's as standard issue.
I found out soon enough though, that they were slightly less than adequate
for the off-roading I get in to. The pic at right is a Goodyear Wrangler
GS-A after stripping off my wheel while climbing a rock wall that offered
fair challenge, but can be crawled up without wheelspin. Also, traction
with the Goodyears was shocking, although through my ignorance I didn't
So after that escapade I started reading up on tyres. I found out about
tread designs. There are five basic tread patterns, with a few sub-classes.
They are generally biased towards excellent performance in one area, but a
careful choice will give you a tyre that is excellent in your particular
environment, and generally ok when you stray from it.
This is an ordinary passenger car tyre and works well on
tar. Potentially useful in sand and certain types of rock
because of its non-aggressive tread, they are often seen
on Freelanders, RAVs, Honda CR-V's, and the like. Beyond
this, they are essentially useless on the trail. There is
no real advantage to having them unless you do very little
or no off-roading.
AT's are designed to perform well in a variety of off-road
conditions. It is a fairly recent innovation that has
closed the highway/trail gap. The closed tread design
performs well on rock and sand, and is usually quiet on
the highway. They are generally decent in rain, snow and
ice. As you'd guess, they tend to load up in mud but some
of the AT designs are suprisingly proficient in the goo.
Mud tyres come in a variety of styles, from the old
bias-ply mudders that give new meaning to the term road
noise, to modern radial designs that are suprisingly
quiet and docile on tar. Apart from their obvious
attributes in mud, they are generally oustanding in rocks
and good in deep snow. The flexible radial MT's can also
be very good in sand, but are at their worst in rain and
especially on ice.
A good snow tyre is not an open-lugged design like a mud
tyre. It is moderately open for self-cleaning, but close
enough to compress the snow inside the tread and use its
cohesion to supply traction. Snow tyres also use sipes
and kerfs. A sub-class are tyres that are rated M&S (Mud
and Snow), which have some potential as a pseudo AT, but
dedicated ST's wear quickly on dry roads.
Sand tyres are designed to compress sand, rather than cut
through it. Sand driving often requires a reduction in
pressure to improve floatation, and as sand driving is often
coupled with driving over rocky terrain, sand tyres tend to
have flexible and robust sidewalls. These tyres wear fast on
tar, and are slightly noisier that their HT counterparts,
although less so than AT's and MT's.
Through reading and surfing the 'net I found out about load and speed
ratings. Every book I found belaboured the difference between cross-ply
and radial tyres. I believe that this is becoming a bit of a dated debate
(cross-ply is out of date, and rarely used).
The 2" lift I'd fitted to the Jeep is significant as this allows me to fit
larger than standard tyres to increase both under-axle
clearance and the Jeep's
breakover angle. Also, I have this
inexplicable fixation with mud and water.
Thus my reading was starting to send me more and more into the direction of
Mudders. I then started thinking about tyre
size. I'd read that with a 2" lift I could safely go with 31x11.50's.
Being in South Africa these numbers meant thing to me, and I then figured
out that these were floatation tyre sizings. I also learnt that a change
in tyre size would change my overall gear
ratio from 3.07:1 to 2.7:1, meaning an indicated 10.4km/h increase
in my speedometer reading at 100km/h.
My concern now was three-fold: one, afternoon thundershowers on the
highveldt are numerous in summer, and MT's don't do that well on wet
tar. Two, I love snow-skiing, so my tyres had to get me to Tiffendell
and back safely. I have a sister who's a PRO for the Higlands Water
Project, so Lesotho ice was also a concern. Everyone I knew, and all
the books I'd read were extolling the bad manners MTs have on ice.
Lastly, as I drive down to Mozambique and the northern parts of KwaZulu
Natal at least four times a year, their performance (or rather, lack of)
on sand was at issue.
Then I discovered siping. Sipes are slits or cuts in the tread blocks that
allow the blocks to move and grip. Siping usually enhances the wet and icy
performance of the tyre, and are sometimes added by the manufacturer but
more often than not added by off-roaders themselves.
By reading through predominantly American newsgroups I discovered Super
Swampers, apparently a good and popular tyre over there. I was specifically
interested in the Radial TSL's. Unfortunately I couldn't find a local
distributer, and with my awesome bank balance I was forced into remebering
the Jeep parts shopper's credo - "the mostest for the leastest". Exit
importing expensive US tyres and enter the BF Goodrich Radial Mud-Terrain
The BFG MTs are obviously good in mud. They have an incredibly
strong and flexible sidewall (3 plies), and are thus very suited to lower
tyre pressures and rock crawling. Sand driving cost me a little more fuel
than normal. While they tend to push quite a lot of sand before them, I
was unable to bog the TJ in 2 wheel drive without a very heavy foot.
Environmentally they're good - the traction provided by the MTs has all but
elimitated wheel-spin, keeping the trail intact. Lastly, siping on the two
center lugs vastly improved hard braking in wet weather, although I have yet
to try them out on ice. They're definitely noisier than HTs and ATs, although
the Jeep's open top and loud music drowns that out.
© 1998-2013 Michael Wittenburg and Martin Wittenburg. All rights reserved.