fuel economy with big tyres

im ready to buy some off road tyres but unsure weather to get at or mt tyres as its my every day car and off roader but when talking to some one he said he lost 5mpg id expect it to drop a bit but i thought was was quite alot is that about right?

yep thats right
when i had the disco on road tyres i got 27- 32 mpg
after i put insa dakars on i got 23-25 mpg
and dakars aren't that aggresive

mickdj said:

im ready to buy some off road tyres but unsure weather to get at or mt tyres as its my every day car and off roader but when talking to some one he said he lost 5mpg id expect it to drop a bit but i thought was was quite alot is that about right?

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There are at least two elements to this question:

1. The size of tyre affects the overall gearing of the transmission. Eg., std tyres for a TDi are 205/80/16 or 235/70/16 both of which have an identical rolling radius. However a very popular aftermarket fitment is 235/85/16 - this increases the rolling radius by almost 10% which reduces revs for a particular gear/roadspeed combo. This sounds good but can be bad for mpg as most owners drive to achieve the performance as they had previous to the change, so they need to give more pedal, not less.

2. Road-only tyres have, obviously, different tread patterns to AT and Mud tyres. What is not so obvious is they are also different in the rubber mix they use, which creates greater rolling resistance for the off-road type of tyre.


I have found the AT tyres from the likes of BF Goddrich and General Grabber offer excellent on-road grip, don't compromise mpg too much and work well off-road also. If the vehicle is your everyday motor I would advise against full Mud tyres, preferring instead AT's

ok thanks for that didnt think about the gearing changing my mpg

fook the fuel economy get the biggest and best tyres you can afford

wiltshire landyman said:

fook the fuel economy get the biggest and best tyres you can afford

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:5biagree: