Had to use the spacesaver on my 1.0 Yaris last year (front wheel). I couldn't believe how I only needed to touch the brake pedal for the ABS to kick in, and was very relieved to get the full size back on.
You are only supposed to use space savers on the back for this very reason - if you have a front puncture transfer a rear wheel to the front and put the space-saver on the rear.
A separate warning to all the Mondeo drivers - what Ford call a full size spare is a different size to the tyres on the car - may be a real tyre but is the wrong size. If you don't believe me go and look!
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You are only supposed to use space savers on the back for this very reason - if you have a front puncture transfer a rear wheel to the front and put the space-saver on the rear.
If the spacesaver is more likely to lock up under braking, then I would want to put it on the front rather than the rear. My logic being that it is very similar to the situation discussed in the recent thread debating which axle new tyres should be fitted to. Losing directional control on the rear axle, as happens when the rear wheels lock is, I think, generally viewed as dangerous.
Perhaps spacesavers are recommended for use on rear tyres because of their (usually) lower loading - particularly on front wheel drive cars?
number_cruncher
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Full size alloy on the Office Cav !!
Too lazy to check the Beemer.
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You are only supposed to use space savers on the back >> for this very reason - if you have a front puncture >> transfer a rear wheel to the front and put the space-saver >> on the rear. If the spacesaver is more likely to lock up under braking, then I would want to put it on the front rather than the rear. My logic being that it is very similar to the situation discussed in the recent thread debating which axle new tyres should be fitted to. Losing directional control on the rear axle, as happens when the rear wheels lock is, I think, generally viewed as dangerous. Perhaps spacesavers are recommended for use on rear tyres because of their (usually) lower loading - particularly on front wheel drive cars? number_cruncher
The debate on which axle to put new tyres on is a totally different situation, it's based on high speed cornering on a wet surface. Anyone who does that with a spacesaver tyre on is not using it for the intended purpose. One wheel locking up on the front is going to cause the car to spin more easily than one of the rears locking up.
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You are only supposed to use space savers on the back for this very reason...
My manual says the spacesaver should be on the front. ISTR it's a slightly different diameter and would cause damage to a limited slip diff.
Martin
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One wheel locking up on the front is going to cause the car to spin more easily than one of the rears locking up.
Sorry kith, I couldn't disagree more.
number_cruncher
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Simple law of physics. Weight behind the pivot point (the one front wheel that has not locked up and is still gripping), weight transfers to front (car spins). Weight in front of the pivot point (the one rear wheel that has not locked up and is still gripping) weight stays in front (car does not spin, just moves off centre). The "weight" being the mass of the car.
Now how does your theory say otherwise ??
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I haven't a clue about even the simplest laws of physics so perhaps that's why I can't understand why the loss of grip on a front spacesaver wheel would cause loss of grip on the two good rear tyres and result in a spin - massive understeer perhaps. However, I can imagine how the loss of grip on a rear spacesaver could reduce the grip at the rear sufficiently to cause a spin.
But then I don't understand how those bloomin' great jumbo jets stay in the air either.
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Must have missed the original spacesaver thread.
My Vectra has 17" alloy rims - fairly substantial wheels and tyres. It also has a spacesaver spare. I've never had to use it yet, but am quite happy about it as I would generally endeavour to get a puncture fixed the same/next day if possible.
Just my opinion but never really seen the point in having a full size spare - especially an alloy, as it never gets used unless you're into rotating your tyres to ensure it does get some use. You're basically wasting a good tyre by leaving it in the boot to perish (and this I think is true based on the number of used cars you come across with brand new, ten year old tyres in the boot) I would not however be happy about having a can of foam instead of a spare - that is a step too far IMO
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It also has a spacesaver spare. I've never had to use it yet, but am quite happy about it as I would generally endeavour to get a puncture fixed the same/next day if possible.
My concerns and what then happens?
1. I get the puncture 100 miles from home outside trading hours.
to stay legal I guess I just crawl home.
2. I damage a sidewall. I am then at the mercy of whatever charges the local tyre fitter chooses.
2a. If I have an uncommon tyre size or spec that is not available. Stay where you are?
If I were to undertake a long trip or visit europe I think I would buy the real thing.
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Those are my feelings also. Sod's law says that if you do get a puncture it will be in the most inconvenient place and at the most inconvenient time - and as an additional bonus it will be the type of puncture that an aeroasol won't fix. Would I be correct in saying that almost any puncture at motorway speed would damage a tyre too much for an aerosol to fix?
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Hi Kith,
I can see how you have arrived at your point of view, but I don't think it is correct - for two reasons, braking and steering.
First braking, if the rear wheels of a car lock up, they lose lateral as well as longitudinal grip - i.e. their ability to keep the rear of the car following the front. The result is that unless skillful corrective steering action is taken, the car will swap ends.
An easy demostration of this can be performed with a matchbox toy car and a smooth board held at an angle so the car will slide down. If you lock up the front wheels of the car, the car will go straight down. If you lock up the rear wheels, the car will tend to swap ends and go down backwards.
To this end, both construction and use regs, and European law makes sure that motor cars must be designed such that the rear wheels will not lock. Hence, load sensing valves and pressure reducing valves.
Now steering, if the rear wheels cannot produce as much lateral grip as they ought to, the car will then tend towards oversteer. Neutral acceleration oversteer, i.e., that not provoked by acceleration or braking is generally agreed to be a bad thing which should be avoided.
number_cruncher
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Not pretending towards any expertise, but I'd go with number Cruncher on this. Having ended up on a motorway bank after a rear tyre blow out I still remember the total loss of control caused by the "Tail wagging the dog effect". At the time I still thought I was fortunate that it was a rear tyre rather than one of the fronts, but when I commented on this to one of the traffic police who turned up he said the worst results were always caused when someone lost the back end as there was much less possibility being able to steer - even partially - out of the problem.
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strange i had a high speed blowout on the m5 in an recent escort, lost a rear tyre, apart from the noise and feeling heavier to steer it was quite easy to guide it over into hard shoulder and parked up ok, wheel was knackered though
when mg metros with TD tyres were the new play thing I had one and lost a back tyre, didnt even notice the noise till a quiet bit of the music, certainly drove perfectly well, although i guess those tyres were designed for it
never lost a front tyre
guess i was just lucky
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Point taken, but are you confusing a puncture with a blow out? Remember when a tyre blows out rather than just deflates you are driving on the wheel rim, with zero adhesion. My experience was about fourteen years ago, and it is probable that improved tyre design ovr the years helps prevent a puncture turning into a total tyre failure.
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definite blow out in the escort, dramtic bang etc
in metro no idea, i had no knowledge as i say until i heard the noise in a quiet part of music, tyre was certainly just shreds by the time i stopped, wheel red hot etc, i guess those TD wheels and tyres were just so good that unless you heard it you could well not know
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Hi number_cruncher,
I still think you're wrong. In your experiment with the matchbox car, you mention locking the front wheels and locking the back wheels, I assume you mean in pairs. The whole point of the post is regarding ONE side of the vehicle having a different tyre (and hence different grip) to the other side. Might I suggest that you repeat your experiment with ONE front wheel locked, then ONE rear wheel and see what happens. The point I'm trying to make is that the car will be more likely to thrown off lateral balance and course by having one front wheel less grippy, under braking, rather than one rear. Two reasons For this are (1) 70% of the braking force is transferred to the front wheels when braking (transfer of weight) and (2) the rear wheels are less likely to lock up and loose grip altogether due to the pressure reducing valve.
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Well, here's a funny thing.
When I ran a Morris Oxford, there was no such thing as a space saver on this car. However, a previous owner had fitted crossplys on the front and radials on the rear.
Hence to be properly covered I had to carry 2 spare wheels!
I did consider replacing the crossplys at the front with radials but I was advised it would adversly affect the handling, whereas the rear wheels would benefit from the more modern radials.
H
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I ran over a sharp bit of Florida on the way to the airport in the dark just after hurricane Charlie. Our rental Chevy had a spacesaver. No way would the shredded tyre (tire?) fit where the spacesaver had been. Rest of journey spent with suitcase on passenger's lap.
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The comment about where to fit the space saver comes from the manual on our Audi A2 which has a Vredenstein collapsible space saver. It has the same diameter as the full size wheel so as not to upset the ESP/ALB/Traction Control etc.
Have not driven it on the space saver but SWMBO has and didn't like the experience. I would not like to brake hard with the space saver on the front! This is also why they are limited to 50mph.
Surprised non of the Mondeo drivers responded to the second point in my post!
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A2 also came with a large, heavy duty, white, Audi branded bin bag to put the dirty wheel into!
www.a2oc.net/pic_showall.asp?cat_id=56&parent_id=7...s
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