The subject of tire deflation is a controversial one. With so many variables at play, many off-road enthusiasts battle to agree on figures. What’s more, with a near-infinite number of terrain types on offer, it’s hard to know what pressure is right for the job.
This point is further complicated by other variables, such as tire size, vehicle mass (including payload) and tire construction (sidewall thickness). Then, one must also consider pressure fluctuations caused by heat and rising road temperatures.
In the end, the art of tire deflation is best mastered through a process of trial and error – one determined by personal preference, vehicle setup, and tire brand. However, to help in this process, here are a few deflation tips to consider…
1) DEFLATION FOR STRENGTH
A deflated A/T (off-road) tire can be (up to) 1000% more puncture-resistant than an OE fitted H/T tire! This is mostly due to the tire becoming more subtle and “malleable” to the terrain, but its also due to better weight distribution thanks to a larger tire footprint.
2) FIT DEDICATED OFF-ROAD TIRES
Unfortunately, a number of all-terrains look like off-road tires as far as tread design is concerned, but in terms of durability, weight, and puncture resistance, they’re no different to a high-way terrain. For example: Using a 265/65/17 as an example, the Cooper S/T Maxx weighs 24.5 kg, while many OE specced all-terrains are little more 18 kg.
That said, the difference is usually a matter of Light Truck tires versus Passenger-carcass alternatives. Be sure to look for the letters “LT” on the tire’s sidewall.
3) ALWAYS DEFLATE
Most vehicle manufacturers will tell you to stick to your vehicle’s recommended tire pressure – as per the service manual. However, most 4x4 training courses advise that your tires be deflated when driving off-road. The information is conflicting, but rest assured, a deflated tire offers considerably more traction off-road.
If you’re still undecided, don’t let traction be your motivating factor, consider the environment. A deflated tyre is safer, more comfortable, and far less harmful to the environment.
4) SMALL CHANGES, BIG RESULTS
Don’t underestimate the impact of a small tire-pressure change, even if it’s just 0.2 Bar. For example, what may not be possible at 1.0 bar, could be a breeze at 0.8 bar.
5) AVOID SHARP TURNS
Never perform a sharp turn if your tires are deflated below 1.2 bar – doing so will place pressure on the tire’s sidewall and may cause it to de-bead off the rim.
6) FRONT & REAR
Your 4x4’s rear tires can be deflated slightly more than the front tires; this is because the rear tires are not subjected to turns and sidewall load. This is especially the case when driving in soft sand.
7) GOING BY SIGHT
If you don’t have a tire pressure gauge with you, and you’re about to drive over sharp rocks, stop deflating the moment you notice the tire bulging at the sidewall.
8) ESSENTIAL GEAR
Always travel with an accurate tyre-pressure gauge, a heavy-duty compressor, and a puncture-repair kit in your 4x4.
9) SPEED KILLS
No matter what the terrain type, never drive a deflated tire at speed, doing so will cause heat build up, irreparable damage, and ultimate tire failure.
10) GRAVEL TRAVEL
A small decrease in tire pressure will dramatically improve your vehicle’s gravel-driving performance and road comfort – especially over corrugations.
11) TURNING BLUE
If your deflated tires take on a blue-ish tone, chances are they’re under-inflated and overheating. Reduce your speed, or re-inflate a bit.
12) OVER THE TOP
Always drive OVER sharp obstacles rather than trying to squeeze around them. The tread is the strongest part of a tire, and it can also be repaired when damaged. In contrast, the sidewall is a tire’s weakest and most vulnerable area, and it can’t be repaired. If in doubt, drive over, not around.
13) IT’S ABOUT LENGTH, NOT WIDTH
The performance advantage of deflating one’s tires is linked to an increase in tread length – as the tire deflates – and not tread width.
14) TIRE CONSTRUCTION
Tire construction greatly influences how a tire will react to deflation. Some tyres use a robust carcass that requires additional deflation in order to achieve the same “stretched-out” result. What’s more, a road-biased H/T tire with a 2-ply sidewall rating will require less deflating than an A/T or M/T tire with 3-ply sidewall.
15) APPROXIMATE DEFLATION GUIDE
Bitumen: 100% (Manufacturer’s recommendation)
Gravel: 10 – 15%
Corrugated dirt tracks: 10 – 15%
Sharp rocks: 10 – 15%
Smooth rocks: 20 – 50%
Sand: 50 – 60%
Original published here.
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