Which 4WD tyres will improve fuel economy in my Toyota Prado?
QUESTION
Hello John,
I would like you to do a YouTube story that applies your understanding of physics and engineering to the rolling resistance of tyres in relation to fuel economy implications. We all buy tyres with minimal thought to this issue. I am not sure if you also lobby the government regulators, but it would be nice to have a similar mandatory tyre labelling scheme that is in place in the EU.
The reason for this request is that I need a new set of tyres for my Prado, which came with quiet and fuel efficient highway terrain tyres. If I followed the pack, I would get all-terrain BFG K02 tyres. These K02 tyres are seriously strong and well designed for off road conditions but, there are lots of reports that they increase the vehicle’s fuel consumption by 10%. This 10% increase in fuel adds up to a lot of coin when at least 90% of this fuel is used driving on the bitumen.
I’m still going to buy all-terrain off-road tyres, but I’m happy to sacrifice some tyre strength that I don’t actually need for better fuel economy and longer range from a tank full of fuel. The problem is, I am guessing, the tyres sold in the UK/EU are potentially not the same as the tyres sold here in Australia to make my decision on.
Best regards,
Simon
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ANSWER
Simon,
There’s no shortage of people who’d like me to do this or that. I’m a one-man band, dude, and I fundamentally disagree with you on a number of points.
Say you’ve got a five-year-old Prado with fuel economy of 10L/100km real world, and you do 20,000km/yr, which is roughly 33% above the national average. That’s 2000 litres per year of fuel. Call it $4000 in fuel, at $2 per litre.
That 10% increase is $8/wk. That’s bugger-all, respectfully. It’s two coffees, or one really cheap bottle of red wine. It’s not ‘a lot of coin’, as you suggest.
If you really care about fuel economy, you wouldn’t own a 2.3 tonne LandCruiser Prado. I’m not having a shot at you; I’m sure the vehicle serves your needs. You simply cannot give a shit about fuel economy and choose to own a vehicle such as that without being misguided or defeating your own ambitions.
Also, even at today’s prices, fuel is very cheap in the context of what it does. Australia also has very cheap fuel compared with most of the rest of the world.
I’d suggest you REALLY don’t give a damn about fuel economy if you are going to continue to buy all-terrain tyres. This is just a fact. They are the least economical tyres you could possibly buy before going to hardcore mud tyres.
The design trade-off with all-terrain tyres is not between strength and economy in any case. Rolling resistance is a consequence of hysteresis in tyres (Part II is here). The solution is not ‘weaker’ tyres; it’s more advanced materials (typically with high silica content). This costs more. The cost increase typically negates the cost benefit of fuel saved.
If you want to do anything meaningful toward saving fuel with any tyre, make sure they are properly inflated at all times, checking them once a fortnight. Then, you can further contribute to fuel-saving by changing the way you drive - accelerate more gently, look further up the road in order to predict sooner what the traffic does (which will force you to take your foot off the throttle) and remove any unnecessary weight from the vehicle whenever you’re driving. Remember, the throttle is a fuel delivery system.
This is not what you want to hear, I know, but I’m a ‘facts’ guy, not an ‘every kid gets a medal’ appeasement guy.
JC
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