Technical Tyre size

[joemorris1]

Hi, I have 195/70R on my van, I understand I can put 205/70 on. Would the larger size make any difference to fuel consumption?

 

[corcai]

Hi, I have 195/70R on my van, I understand I can put 205/70 on. Would the larger size make any difference to fuel consumption?

Insignificant difference. Increase in circumference is only approx 2% so not significant change to revs, sidewalls approx 4% taller sidewall and larger contact patch so slightly more energy lost there. The 205s are noticeably more comfortable on uneven roads though.

 

[joemorris1]

Thanks for the answer, as there is not a lot of difference in price I think I will put 205s on when I renew.

 

[rolandbrindley]

I changed the tyre size on my 1993 TD10 from the factory issue 185/80R14 to 195/70R14 as the standard tyres were becoming hard to source here in Almeria. Then I found out that the spare wheel would no longer fit in the underbonnet cradle which is only just wide enough for the standard tyre, the extra 10mm being too much. So now it has to live inside, something of a nuisance at times. I checked with the vehicle testing centre before making this change, and the rolling diameter was found to be within their permitted tolerance, but they told me that 205/70R14 would NOT be allowed and would cause a test failure. Be warned!

 

[corcai]

The 205 70 14 is smaller diameter than the 185 80 14 so its not the diameter. might be that the rims were too narrow for the 205s or that they would have protruded beyond the fenders.

 

[Crossingkeeper]

Then I found out that the spare wheel would no longer fit in the underbonnet cradle which is only just wide enough for the standard tyre, the extra 10mm being too much. So now it has to live inside, something of a nuisance at times.

I have this self same issue with the old Rover I own and one solution is to store the spare in a partially deflated state and carry a 12v compressor.

 

[rolandbrindley]

Well keeping it deflated is all very well, but having to wait for my pump to blow it up at the side of a busy road in the wind and rain at night doesn't appeal, I'll alter the cradle somehow to take the tyre I now have fitted.