driving on a different size tire

[ericcs]

my son need to drive his bora on it's spare for several days. it's on the front, but before stuffing swapping back to front, then vice versa, is it safe to drive with the spare being only 8.5mm smaller in total wheel circumference 1993.3/2001.8mm, or 3mm diameter?

[ian]

Mate I wouldn't drive with two different circumference wheels on the front ,as you are likely to damage the Differential, swap it to the free spinning rear .

[dylan8]

should always put the space saver on the back from memory.
VW put it there so its ok to drive on, but I would be getting it fixed and off the car asap

[Guest001]

my son need to drive his bora on it's spare for several days. it's on the front, but before stuffing swapping back to front, then vice versa, is it safe to drive with the spare being only 8.5mm smaller in total wheel circumference 1993.3/2001.8mm, or 3mm diameter?

If its only 3mm diameter it wont matter as thats less then the difference between a new and a worn tyre
Will be just like driving around a large corner and thats what a diff is for isnt it.

A new tyre has approx 8mm of tread on it

[ericcs]

should always put the space saver on the back from memory.
VW put it there so its ok to drive on, but I would be getting it fixed and off the car asap

it has a full size spare with a 195/65/15 unused tire on

[ericcs]

If its only 3mm diameter it wont matter as thats less then the difference between a new and a worn tyre
Will be just like driving around a large corner and thats what a diff is for isnt it.

A new tyre has approx 8mm of tread on it

i was thinking along this line also, especially if you have an under inflated tire, the radius can be a lot less than 3mm

[Guest001]

i was thinking along this line also, especially if you have an under inflated tire, the radius can be a lot less than 3mm

Radius doesnt matter its The DIAMETER that does as it does a different number of revs per kilometer and will there fore make the diff work a very slight bit harder

[xpeesx]

Space savers help you 'limp' to the next point of repair. If you think you really need to drive on one for a couple of days, just to be sure, put the spare on the back. it will take 10 minutes max.

EDIT!!! MY BAD, IT'S NOT A SPACE SAVER...

[Lynchy]

Just spent like 5 days hammering a 195/65/15 spare, my diff didn't explode (Y)

[leighaus]

im guessing the (y) stands for 'yet'

[kaanage]

Radius doesnt matter its The DIAMETER that does as it does a different number of revs per kilometer and will there fore make the diff work a very slight bit harder

Diameter = 2 x radius. I suspect your meant circumference which is the length around the perimeter of the tyre but this = 2 x pi x radius (or pi * diameter), so the difference in radius is directly proportional to the difference in circumference.

[ericcs]

Diameter = 2 x radius. I suspect your meant circumference which is the length around the perimeter of the tyre but this = 2 x pi x radius (or pi * diameter), so the difference in radius is directly proportional to the difference in circumference.

the diameter difference is only 3mm, and the circumference 8.5mm as per online conversion chart

195/65/15 v 225/40/18

[dylan8]

the diameter difference is only 3mm, and the circumference 8.5mm as per online conversion chart

195/65/15 v 225/40/18

youll be fine.
iv seen 4 different size tyres come off a 4mo bora once.
if you did it for long enough there would be odd wear on either the 225/40 or the 195/65

[Guest001]

Diameter = 2 x radius. I suspect your meant circumference which is the length around the perimeter of the tyre but this = 2 x pi x radius (or pi * diameter), so the difference in radius is directly proportional to the difference in circumference.

One alters the other. If your radius is 1.5mm larger your diameter will be 3mm larger and your circumference will also increase and therefore will do less turns per kilometer. Normally most people refer to the Diameter when talking tyre sizes. Thats all I was meaning.

In the OP's case it wont make enough difference to matter. Lots of people use an old worn tyre for a spare and have no hesitation using it, if needed the day after putting new tyres on the vehicle. It could therefore have a difference in diameter of up to 12 mm.
Havent heard of any diffs going bang.

[ericcs]

it's only going to be driven to work and back till 18"er get it's crack welded. 18" + 40 series tires + pothole = bent/cracked rim/$120 repair