Safe Speed Forums

The front/rear blow out question depends on what you're going to do with the brake. If you're going to panic and brake then a front wheel blow-out is pretty bad. When the weight transfers forward, one side drops and the steering might go anywhere. But if you're panic braking then a rear wheel blow out is minimised .

On the other hand, if you're not going to panic brake the rear wheel blow out is far more likely to cause a spin.

I did have a very nasty experience with a rear tyre gradual deflation on a very windy night driving down the M11. I knew the car wasn't behaving normally but I put it down to the wind. I found out things were not right on that long left hand bend at the south end of the motorway. It's a good job there was no other traffic nearby because it too plenty of space to gather it up.

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Paul Smith
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Sorry, I meant to add a huge caveat to my last post, to reiterate that it was only stuff I'd read reported, and not based on any sort of personal experience. Touch wood I've never yet suffered any tyre deflation that was so rapid as to present any sort of problem in controlling, so it was very much theoretical on my part.

The thing about the tyre fitters was from personal experience though. I got a pair of tyres replaced on my last car and the fitter absolutely insisted on putting the two brand new ones on the back, leaving the two on the front with about 3mm of tread remaining. FWIW, what had previously been a superb handling car now felt very nervous in the wet, with very "mushy" steering. A few weeks later I swapped them back and the car felt much better balanced.

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Yeah. I wouldn't have let them do that. Tyres wear to suit the suspension geometry - moving tryes from one axle to another starts a fresh 'wear to suit' process. Experience suggests that old tyres are much slower to adapt than new tyres - maybe that's because new tyres never have an 'opposite' shape?

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Paul Smith
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Space savers are pumped up substantially higher in pressure. they have much lower trapped volume of air and therefore are MUCH more likely to be dramatically wrong in prerssure between pumpups than a normal one.

First , lets look at how often we get punctures - i don't seem to get them very often, so a ss would suit me.
But, ( and theres always a but) my ss would spend a lot of its life in the boot. -Problem no 1 - how long before my ss( cost saver) would be dangerous to fit due to age - I don't know , and don't want to find out.
Similar idea for a conventional spare, but usually tyres wear in pairs - i change the pair , and rotate the spare into use. That way i've got good tyres all round all of the time - with a big plus - a prime time for punctures is in the wet - tyres which laugh at a nail in the dry suffer .
This way i know that i have 4 good tyres on and the handling will only be marginally poorer as i have fitted a brand new tyre.
If the punctured tyre has a lot of tread, i leave it in the boot after repair. If not it goes back on the wheel it came off.
My first car had an odd mix on the rear (and it was rwd) , i didnt notice as green . Both had plenty of tread , so all was well i thought, till it snowed - the car then had a mind of its own.
Exactly the same as a ss tyre, IMHO.

Most new cars apart from entry-level models now have alloy wheels, generally with a steel spare, even if full-sized. Therefore "rotating the spare" isn't as straightforward as it once was.

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"Show me someone who says that they have never exceeded a speed limit, and I'll show you a liar, or a menace." (Austin Williams - Director, Transport Research Group)

Any views expressed in this post are personal opinions and may not represent the views of Safe Speed

Simple - buy alloy spare or buy one with steel wheels - cant see the purpose of alloys - look nice , but as always somat else to nick , and we aint got a wheel nicker camera out so you wont get any joy out of plod.

Sorry to be so sarcastic - daughter + 50 others in street ust had a window each smashed, thats after a spate of tyre slashing. But cameras ont catch this, so there's no money to be made.

"Space Savers are only supposed to get you to the nearest garage"

I had a wheel go pop on a Sunday afternoon on my car (Subaru Legacy B4) just after getting off the M3 on the way home to Aylesbury from Southampton.

The wheel is rated for 100KM which I worked out at about 60mph, but even at 50 the back end was all over the place and of course no garages are open on a Sunday. I had to do 50 miles on this thing.

Monday morning, before work, I phoned around, of course no garage stocks 225/50/ZR17s so they would have to order some for midday tomorrow. I had a job to do in Essex that day!

I don't really want to contemplate the number of miles I ended up driving on that thing! and I find it somewhat disturbing that space savers are most commonly supplied with performance cars (because of the enormously wide tyres used) for which tyres are not readily available.

if anyone can point me at a supplier of steel wheels that match the dimensions of my alloys I would seriously appreciate it.

Wouldn't go as far as call them garages but kwikfit and Motosave are open on a Sunday around here.


But I doubt they can get unusual sizes on a Sunday.



Sorry to get all mumsy on you but, from a safety point of view you should really have found alternative transport. You wouldn't have continued driving with a blown head gasket or a faulty alternator. Tyres are a vital component just like any other.

I happen to like the threads on my wheel bolts and would like to keep them



I agree with you, unfortunately my boss did not.
Fortunately however, the speed of the M25 that day was well within the safe driving speed of the space saver. For the other two components you mention, my breakdown cover would have provided another car, but not for a popped tyre. (unless it was the second one to go)

had one in my Audi. i hated it and am so glad i never needed the thing. if i did need to use it, i would have swapped wheels around and made sure it went on the back axle. i would never use it on a steering axle or driving axle if avoidable.
my present car is rear wheel drive but it comes with a proper spare anyway

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Thanks for all the input, unfortunately, the accountants ruled over H&S, since then we have had one accident with one vehicle (correctly loaded with a 'proper' wheel but overloaded with a SSST) (and fortunately not serious for the driver, but the bodywork was a mess).

We are finally getting proper spares !!!!

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I've got a space saver with my mk3 Golf and although it looked utterly ridiculous when fitted, it didn't affect the handling very much the one time I had to use it.

Under normal circumstances you would hardly notice it but they are speed limited and on the minimum legal tread depth from new.

In adverse conditions, rain, snow, ice. Or emergency braking I would not trust one.

My wife has an MG TF. Her car has wider wheels at the back as stock. The tyres are also "directional". Therefore the spare only fits correctly in one location on the car. It is painted black to identify it as a spare. I would rather have that than a space saver though.

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Is a space-saver defined as any spare wheel that has a narrower width than the normal wheels?

I must admit I didn't realise I had a spare with a different width until I recently got a puncture. My normal tyres are 225-width, and the spare is only 205 (with 80 km/h max. speed warning).
As this happened on a Saturday I had a similar problem to Lum in that 225/40s aren't exactly common tyres so I had to live with it for the weekend - however I was surprised at the change in handling it made by putting it on (obviously I was only travelling at modest speeds but it was still noticeable).

[pedant]no, because if it was wider than the normal wheels it could hardly be considered to be saving space [/pedant]

a 205 replacing a 225 probably isn't quite so bad, my space saver looks like it belongs on a 2CV or something.

D'Oh! Edited for clarity..
That's the image I've always had of proper space-savers.. Wouldn't fancy one of those..

oooh.. just to stick my oar in here (as a vehicle dynamicist).

i generally agree.
if you lose a tyre you lose its ability to generate stabilising lateral forces, in the same was as locking or spinning a wheel. in braking legislation the front wheels _must_ lock first (base brakes, no abs) as this is considered the safe condition, i.e. vehicle goes in predictable straight line. if the back wheels lock you lose lateral stability on the rear so it oversteers, or the back end is brought round by any small disturbance.

so on that basis losing half your lateral stability on the front gives the more predictable response. how the steering itself responds would vary on dependant on the vehicle's steering & suspension geometry so it's hard to generalise.

as for braking with a blowout obviously you are now lacking the brake forces from that tyre so any braking is going to be uneven and start to spin the car. since the majority of braking force comes from the front the effect would be more severe with a front blowout.
(it's this aspect that worried me most about driver's response to a blowout, most peoples initial reaction is likely to be to get stationary as quickly as possible)

so keeping it gentle to give yourself time to compensate with the steering would be the key.
i've often wondered about using the handbrake (gently!) in a front blowout condition to slow the vehicle since that would give a balanced braking force at the rear, albeit at the risk of reduced stability on the rear.
fortunately i've not needed to test this theory to date!


ok, carry on as you were

I reckon not. Of course locking up the rears would be pretty unhelpful, but let's assume that you use the handbrake sensitively without causing a lockup. The handbrake is still going to cause forwards weight transfer which will increase the problems at the front end. What we need to try and do is bring it to rest gently and in a safe position. I suggest that easing off the power and concentrating on steering to safety is likely to be the best option. It will still steer, but it'll probably be trying to wrench the steering wheel out of your hands. Don't let go! Don't stop steering!

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Paul Smith
Our scrap speed cameras petition got over 28,000 sigs
The Safe Speed campaign demands a return to intelligent road safety

well quite... we're not in an ideal situation to start with.

_any_ kind of deccel is going to shift weight forwards to an extent, even easing off the power. and trust me, there's quite alot of control available on the handbrake