Tyres: What’s in some black stuff?
OK, so the obvious answer is rubber, but it’s a lot more complicated than that. I’m not going into the ins and outs of rubber compounds here, mostly because I don’t know enough about it. What is worth discussing for a starter is why remoulds aren’t as good as new tyres.
First up what’s happened with a remould is that a load of rubber has been poured into a mould with an effectively worn out tyre carcass in the middle of it. Look at the prices of these tyres and you can see that probably a lot less technology and effort went into ‘recoating’ a tyre than making a whole new one and it’s true.
The cheap price means a lower quality rubber compound will be used, that’s nowhere nearly as advanced as that used by the big brands. The likely implications of this are that it’s not going to be as durable, puncture resistant or flexible as a new tyre. It’s that last attribute that’s the most important when considering the tyres’ out-and-out performance off the road. The tread blocks on the tyre need to be able to flex, this enables them to ‘hang on’ to things and shape around them and also (very importantly) to flex and drop the muck they’ve collected back out from the gaps.
There’s also the chance that your nice new remoulds might ‘delaminate’, that is the new rubber might peel away from the old carcass, trashing an undamaged tyre. This is quite rare, but does happen.
So, they’ll wear faster than branded tyres, won’t hang on as well, might fall to pieces and will be more susceptible to punctures as well. Why is it that so many people buy remoulds to use off road, then? They’re cheap! Yes, it’s purely on budget. This is especially pertinent on Syncros as if you trash one of your £100+ BFG Mud Terrains then you’ll have to go buy another £100+ BFG mud terrain and then get it shaved down to match the other four – double ouch! Trash one of your £30 Colways and, well it’s £30 plus a little bit to get it shaved down to match – not such a big deal.
Another factor is that if you make a nice aggressive design, similar to a well-proven big brand design then chances are it’ll work pretty well off road too. Just look at the Colway MT tyres and compare them to the BFG Mud Terrains – with the exception of some of the tricker features they appear identical.
So what are you looking for in an off road tyre? Before we can answer that question it’s important to look at how you’re going to be looking to use this tyre overall, not just off the road. If the vehicle’s going to be used principally for playing off road then go for something aggressive. If you’re going to put it into daily use then ask yourself how far you’re prepared to compromise ride comfort and handling. A tyre with aggressive treads will put a lot less rubber in contact with the road, diminishing road handling proportionally. You might well not be prepared to make that compromise if your vehicle is going to be seeing more wet roundabouts than tight turns in the mud.
Can you afford to run two sets of tyres? No tyre can be all things to all conditions. If your vehicle is going to be a daily driver then you should consider running two sets of tyres and keep one set to use specifically for playing. Mercedes steel rims offer a cheap solution in this situation, but as they’re made of flexible steel and were designed for road car use don’t expect them to handle the same abuse as a set of heavy duty alloy wheels….. again the cost factor comes into play. At £10-20 per rim you can trash several rims before you’ve run up the cost of a single alloy. It makes a lot of sense unless you’re going on a major road trip when a single failure could be disastrous. Tread design
The design of the tread will be THE SINGLE biggest factor in the performance of your vehicle off road, so choose carefully. A lot of how the tyre will perform in UK conditions is dictated by the tread-block spacing. The UK has a lot of mud, so that’s really what you need to kit yourself up to deal with. What I’ll do is list some generic tyre designs off, with their attributes, which should give you a good understanding of their capabilities. We’ll start with the least aggressive and work upwards:
AT or All Terrain – This sort of tyre is supposedly designed for use 80% on road 20% off road. I’d hope that the 20% off road is some nice gravel surfaces, as due to the linked and close tread-blocks ATs will fill up with mud at the drop of a hat and leave you floundering very quickly.
MT or Mud Terrain – a nice basic (some might say classic) off road design. The open side blocks provide grip to pull your vehicle out of ruts and will shed mud a lot more effectively than the linked blocks of an AT design. MT designs have been around for decades, which demonstrates how effective they are, but also illustrates how archaic their design is.
Amazon/Macho design – These tyres were much feted by the comp-safari racing fraternity about five years ago. They have more tread and less air than the more extreme design, but due to their relatively recent design they self-clean well in all but the most sticky mud and will acquit themselves very well off road. Do bear in mind that these are directional, so unless you have a tyre-changing machine with you you’ll need to have two spares, one for either side!
SAT- type/Mudplugga design – These tyres have rather fallen from favour. They were very much THE tyre in the early 90’s. The Super All Terrain tread was designed to be more aggressive than the MT treads, with only a small width of central tread and wide, separated paddles at the sides they took the concept of the MT and sort of ‘maxed’ it. Michelin XCLs are of similar vintage and capabilities. The downside of both of these designs was that their road manners were appalling, due to the lack of rubber on the road, they also wore pretty quickly, too. These tyres are also directional.
‘Edge’ tyres – BFG called them the Trac-Edge, remoulders imitated this, making them easier to identify when browsing catalogues. This is a later design than the SATs, so you will start to see more ‘computer-designed’ attributes in the tyres. They’re designed to self clean, rather than dig, so when your tread-blocks come back round for another go they’ve got the free air gaps that allow them to grab.
Diamond Tyres – these tyres are chosen by many comp-safari racers today, they are an extremely open design, that allows them to grab and clean exceptionally well off road, but be warned, all that air will provide you with awful grip on the road, reducing lateral grip and increasing braking distances substantially.
Another factor in choosing your tyres is economy. You will get noticeably less MPG on aggressive tyres than ATs, this is because you’re increasing rolling weight and resistance with those lovely tall, open tread blocks. This is another good reason to run two set of treads. One on and one off road suited.
The pressure of your tyres will affect the handling and capabilities of your vehicle where-ever it is.
On road higher pressures will lower the rolling resistance and stop them slopping around, but after a point it will reduce grip as the tyre cannot flex to provide grip in corners.
Off road the differences are even greater. Low pressures allow the tyre to shape to the ground and let the tread-blocks flex to spit out the muck.
What should also be considered when fitting larger tyres is that with the increased air pocket you will be able to reduce the pressure, as there’s more air suspending the vehicle over a larger contact patch – this is another contributory factor in your tyre choice. Wider tyres will spread the load of your vehicle more, reducing the tendancy to ‘bog down’ or ‘cut in’ to the ground.