SpaceSaver tyre - size - OK to use

castle96

Mitsubishi Eclipse Cross. Front wheel drive
Had to change tyre (215/70R 16 100H) on front - pucture.
I bought a s/saver 3 yrs ago/internet/gave them full details... T155/90 D16  110M.
I see the 16 in each description (though the s/saver 'looks' smaller. Need to drive to garage to get puncture fixed. 
IS the s/saver compatable? Dont want to damage anything. If it was a smaller wheel, surely I would. Worried

Nobbie1967

The space saver has a slightly smaller rolling radius as the tyre has a shorter sidewall. Should be fine for a short drive to the garage, although you may get a TPMS tyre warning (if fitted) as the car will think you have a flat tire due to the different rolling radius.

Ganga

How far is the garage from where you keep the car ?

Ectophile

The 16 is the size of the wheel rim, in inches.  So it's the same as the full size one.  The first two numbers on the tyre describe the width (in millimetres) and the profile (height, as a percentage of the width) of the tyre.

So long as the wheel rim actually fits properly on your car, it should be OK for a short drive.

facade

Space savers are often miles smaller both in diameter and width than the "proper" wheel, they are an emergency measure to get the car to a garage that can repair the punctured tyre- at low speed.

The online handbook (I checked the 2018 MY) says to be careful as the  small thin wheel will give reduced ground clearance!

It doesn't say anything about only fitting the space saver to the back, so it seems fine to just drive the thing to a garage, but take it easy, as the thinner tyre will have much less grip than a "proper" one, and the TPMS will alarm.

Goudy

facade said:

It doesn't say anything about only fitting the space saver to the back, so it seems fine to just drive the thing to a garage, but take it easy, as the thinner tyre will have much less grip than a "proper" one, and the TPMS will alarm.

It is sometimes the only choice to fit them to the rear.
It all depends on the size and offset of the space saver and the cars brakes.

Not all space savers will fit over the front brakes.
Cars generally have bigger brakes at the front than the rear and you would think the manufacturer would supply a space saver to fit both ends.

But some trim levels of the same car might have bigger front brakes than all the rest of the trims, like the sporty trims.

They can often come with the same standard space saver that all the other trims have, as they save money with scale. So they will only fit the rear.
In an emergency with a flat front, you have to change the rear over and fit the good rear to the front.

I once stopped at a motorway services and noticed someone struggling by the petrol station changing a wheel.
They couldn't get the space saver on the front of their sporty Civic and were pretty flustered.

I pointed out to them they need to refit the flat front, swap one of the rears with the space saver and then swap the flat front with the good rear.
It didn't go down well, the young chap was ready to explode but they managed to do it and were on their way again, slowly.

BMW's are notorious for this as lots of models have 380mm or larger discs on the front, yet the space saver they come with are tiny and they all seem to come with the same space saver.

facade

Goudy said:

facade said:

It doesn't say anything about only fitting the space saver to the back, so it seems fine to just drive the thing to a garage, but take it easy, as the thinner tyre will have much less grip than a "proper" one, and the TPMS will alarm.

It is sometimes the only choice to fit them to the rear.
It all depends on the size and offset of the space saver and the cars brakes.

Not all space savers will fit over the front brakes.
Cars generally have bigger brakes at the front than the rear and you would think the manufacturer would supply a space saver to fit both ends.

But some trim levels of the same car might have bigger front brakes than all the rest of the trims, like the sporty trims.

They can often come with the same standard space saver that all the other trims have, as they save money with scale. So they will only fit the rear.
In an emergency with a flat front, you have to change the rear over and fit the good rear to the front.

I once stopped at a motorway services and noticed someone struggling by the petrol station changing a wheel.
They couldn't get the space saver on the front of their sporty Civic and were pretty flustered.

I pointed out to them they need to refit the flat front, swap one of the rears with the space saver and then swap the flat front with the good rear.
It didn't go down well, the young chap was ready to explode but they managed to do it and were on their way again, slowly.

BMW's are notorious for this as lots of models have 380mm or larger discs on the front, yet the space saver they come with are tiny and they all seem to come with the same space saver.

I didn't realise that was the reason. I assumed it was because the enormous difference in grip between the tyres would reduce the braking effort on the front to dangerously low levels.

My woeful Renault Nissan insists the spacesaver has to go on the back, yet I've ridden push bikes with bigger discs

A colleague had one of the first A class Mercs, and fitted the space saver. Cost him a fortune as unknown to him the space saver needed the special short bolts from the toolkit and it bent them over and damaged the hub....

Goudy

It does seem common now that handbooks state they should always go on the rear even though they will obviously fit the front as well.
I'm not sure if that is due to scale as well, one hand book suits every model or that some cars, like FWD ones might be better with two full sizes at the front as they take care of the power, steering and most of the braking.

Though I think a lot of RWD BMW handbooks I've seen say fit them to the rear as well??

I would follow the handbook if I could, but as already mentioned there are models where they just won't fit the fronts due to the brake discs and calipers.

I have used them once or twice, but only for a 1/4 of a mile and if it fitted where the flat was, I just fitted on there.
If I had a flat on a motorway I'd ring the breakdown company, no way I'd try swapping a wheel on there.

I've got out of trouble once or twice with "dog turds" (look them up).
Handy if you pick up a screw or nail and the tyre can often be repaired properly later, if the puncture isn't too near the shoulder.

fatbelly

215/70 has a radius of 150.5mm

155/90 has a radius of 139.5 mm

That's a difference of 11mm. If the spare is new and the other tyre on the axle part-worn that could reduce to 7mm.

Honestly you won't notice the difference as long as you are not exploring the new handling and braking limits