Sorting one problem has created a new one !

[M 80NGO]

Ordered my new tyres 235/45/18 XL98 on saturday evening only to realise sunday that i have created myself a whole new problem

My new 235/45/18 Nangkang tyres have a rolling radius of 210.08 cm, they are the correct load rating and they'll help eliminate my 10% over on the speedo, so life is all gooooood

However ! My 215/65/15 nangkang spare has a rolling radius of 207.50cm (3 cm smaller) which ordinarily wouldn't really bother me but my beloved L'oreal is fulltime 4wd and i really don't want to go across france later this year with a spare wheel that is about as much use as a choccy teapot cos if i have to use it then i risk shafting the 4wd system.

There is a solution which is to remove my spare tyre and replace it with a 205/70/15 which has a rolling radius of 209.86cm just .22 of a cm differance they're easy enough to come by it's just added expence that i don't really need


That's the wonderfull world of moddifying i guess

[Jim the Box]

Does the bigger rolling radius have any effect on mpg, and what effect does it have on acceleration?

Jim.

[M 80NGO]

Does the bigger rolling radius have any effect on mpg, and what effect does it have on acceleration?

Jim.

The bigger r/r should make it more fuel efficient on a run as she'll be reving slightly lower due to the extra 3cm and yes it will slightly decrease the acceleration but then l'oreal was never gonna blitz the quarter mile she's built for comfort not speed

But to be honest this excersise is more about getting l'oreal wearing the right grade of rubber rather than getting her to run quicker .

[westonwarrior]

from new it would have had a space saver which is very different in radius

Just use the spare to get you to a place where you can repair or replace the good tyre.

[Northern Bongolow]

a 205 70 15 is the same as your new ones.

[M 80NGO]

Yeah i've done the tyre radius maths and the 205 70 15 tyre is the same albeit .22 of a CM differance tho instead of carrying a spare i did think about carrying a tyre repair kit




http://www.ebay.co.uk/itm/12V-MINI-COMP ... 3f1555acb7

http://www.ebay.co.uk/itm/2-X-CAR-TYRE- ... 231a7ebae9

What pressures should i be running my new rubber at ?

[francophile1947]

What pressures should i be running my new rubber at ?

Anybody's guess - just adjust them until they feel right.
I ran my 17" tyres at 40psi all around, so that would probably be a good starting point.

[M 80NGO]

What pressures should i be running my new rubber at ?

Anybody's guess - just adjust them until they feel right.
I ran my 17" tyres at 40psi all around, so that would probably be a good starting point.

Cool ! thats what we'll start with then