Mazda Mazda 6 (2002 - 2007) - 04 2.3 Zugara - Tyres

Honest John Back Room » Technical matters
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Mon 23 Jun 2008 15:33
04 2.3 Zugara - Tyres - Tuppytrucker
The tyre tread depths on our Zugara are coming down to around 3mm and will soon need replacing. The car is fitted with OEM Bridgestones 215/45-18. According to the owners manual and the tyre label fitted to the car, this is the correct size. When I was doing my research for buying the replacemnt tyres, all the sellers websites came up with a different size - 225/40-18. I've used the tyre calculator at www.miata.net/garage/tirecalc.html to compare the tyres.
The wrong size is a much cheaper tyre than the original and only differs in rolling circumference by -2%. However, this means a 2% increase in fuel consumption. Opting for the wrong size will save around £120 for a set of tyres but inrease the fuel bill by 2%.
Any thoughts?
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Mon 23 Jun 2008 15:39
04 2.3 Zugara - Tyres - shadyarea
Try this site


tinyurl.com/52kg8p
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Mon 23 Jun 2008 19:36
04 2.3 Zugara - Tyres - Dynamic Dave
However this means a 2% increase in fuel consumption.


You've not mentioned how much cheaper the replacement smaller tyre is, but I bet the saving outweighs the increase in fuel consumption. A no brainer and not worth losing any sleep over, IMHO.
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Mon 23 Jun 2008 21:34
04 2.3 Zugara - Tyres - John S
Don't worry about economy. Tyres of the same nominal size but different brands can vary more than that. The minor difference in diameter won't have a comparable effect on fuel consumption. It means the engine will be spinning 2% faster, but throttle will be less far open - the slightly greater frictional losses in the engine and transmission will be insignificant. As an example the 2.0litre Vectra in Sri form had significantly lower gearing than the standard car (22.4/24.8 mile/hr per 1000 revs - a 10% difference), but official fuel consumption was about 2% different and this was not noticeable in practice.

JS
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Mon 23 Jun 2008 21:49
04 2.3 Zugara - Tyres - Screwloose
Tt

Why not just stick with the correct size and make of tyre.

That way you won't have to declare modifications to your insurer and there will be no need to lose sleep over it.
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