Why did I decided to replace my spare with a full size tyre?
This was partly out of necessity, and partly because I’ve always wanted to have a full size spare on my car.
What I recently had an issue with a flat tyre on my car. The tyre has always had a slow puncture, and I pumped it up the day previously, but for whatever reason the tyre was completely flat. I pulled away and heard a rattling type noise, driving slowly but then it disappeared. I never checked the tyre before my morning drive to work, and to my amazement the tyre held out. Although thinking back is what made me so uneasy. I never clicked on when driving. I was doing motorway speeds, and it constantly felt slipping on the back end. The best way to describe it would be if you’ve ever driven in high winds on a motorway, it kinda feels like that. It was a bit of a red herring to me, because I opened the window and it was very windy so I never thought about it.
Basically I kept driving to work and when I was getting to work I still felt something was off, it was only in the last few hundred metres I felt the tell tale symptoms of a lumpy / rock feel from the rear and knew it was a tyre. I pulled up at work, and yep, 0 PSI, it was completely flat.
I pumped up the tyre, and it held pressure to my amazement, it held pressure. However there was a hell of a groove in the sidewall where the tyre was running on the rim all the way. When I was on my lunch, I still felt uncomfortable so went about fitting the replacement wheel
CUE THE SWEARING
This goes to prove you should always trust your instincts, and check the basics. When I removed the spare wheel . I was already irritated, because I always thought I had a flul size spare, and I REALLY REALLY hate space savers with a passion. Not only that I had a widow maker car jack, so was even sketchier to lift up the car. I thought sod it and removed the wheel for replacement
It was only after removing the tyre I saw how bad my wheel had become. I was lucky, VERY VERY LUCKY. The side walls on my car had blebs everywhere (little bubbles on the inside edge) that I couldn’t see. Tyre was deformed, and it was basically flat on the inside edge. I could have had a tyre pop at any point when driving home if I kept using the old tyre on the assumption it was holding the air. The pictures below don’t do justice on how bad the tyre was. On the outside edge, it looked fine. There was just a groove against the sidewall that was worn
The inside edge however there was limps and deformations all over the tyre. When you look at the photos below. The first two photos show the deformations when you look close, and there was a good 10 or 15 sidewall blebs.
I NEED A NEW TYRE!
Hell no! Even worse it was New Years, so most tyre places were shut for Xmas. I really didn’t feel comfortable driving home on the faulty tyre, OR the space saver. So sod it, I tried looking for a mobile tyre fitter, and a local garage which was nearby my workplace, they were shut. I eventually found a mobile tyre fitter. It cost me £163 including call out to get the tyre fitted. Tyre was an average brand (Massimo), but far better than nothing. So approx £70 for the tyre, and guessing £30 call out. I paid £63 for the quick response, convenience of getting home and peace of mind for my own stupidity. I didn’t even hesistate when it came to the price. I’m fortunate enough I had the money for it, however the way I see it is that Tyres, Brakes and Suspension are what keep you on the road and alive. So you shouldn’t screw on with them
FITTING THE NEW TYRE
This is more props to the quality of tyre, when my tyre was being replaced. The internals of the reinforced Michelin Pilot Sport 4 were completely gone (I wish I had some photos to show this), but it must have been a good 3 or 4 handfulls of rubber sitting inside the bottom of the car tyre. I feel this is a testament to just how strong the sidewalls were on my tyre that they managed to keep me alive. So Michelin Pilot Sport 4, I HIGHLY recommend. Great grip in the wet, very hard wearing, and very strong and reliable tyres. Expensive, sure, but worth it. Very.
How much did the full size spare wheel cost me?
I purchased a replacement alloy wheel, and tyre from eBay for a total of £69. As they’re mainly to be used as spares, I wasn’t 100% bothreed on the condition of the alloy wheel, tyre condition would be preferable good but not an overall deciding factor as I’ll most likely replace it with a higher quality tyre for the alloy when I save up some pennies.
The alloy wheel I purchased was a 7.5J x 17 Multispoke alloy wheel, which is basically the same alloys that my car came with when I purchased it. The part number was 4F0601025AK. Whilst it’s not really needed, I felt it was nice to have a matching set of alloys and it’s a bonus when the spare is the same as the ones fitted to the car. The tyre didn’t have too much tread depth on it (about 5mm), however the legal limit is 1.6mm, so it’s good enough for a spare for now, and 5mm of tread on a spare tyre will last forever.
At some point I’ll probably pay to get another Pilotsport 4 fitted to the alloy, because I’m very satisfied with the way the tyres are handling on my car. The car tyre was a 225/50/R17 profile. The ones on my car are 225/45 which is close enough. It basically means they’re both the same width (225mm), the only difference is the sidewall height on my spare tyre is 5% larger than my main tyres (112.5mm deep) versus (101.25mm deep), so 11.25mm (or 1.125cm). Alternatively I’m thinking of getting a full set of Pilot Sport tyres when they get low ,and simply swapping them around so that my spare tyre (which has 5mm, gets a Pilot sport), and then the tyre which I had replaced becomes my new “spare”. Reasoning behind this is it will be worn down to around 7mm, it’s a full size matching fit, just a different brand. Plus the tyre I have for current spare isn’t matching so would need replacing anyway.
How do you read car tyre measurements?
Tyre measurements on cars, are generally read in the following format, I’ll use mine as an example
225/45/R17 91Y XL
This is how it’s broken down when reading it
- 225 = Tyre width in mm
- 45 = Side height, as a percentage of tyre width (225mm x 45% = 101.25mm)
- R17 = Radial tyre, 17″ (R means radial construction, the number after is the size in inches)
- 91 = Load rating per tyre (how much weight the tyre can support per Axle), 91 is 615kg
- Y = Speed rating of tyre. I can’t remember this number exactly I believe it’s around 180mph
- XL = Reinforced tyre, overall stiffer construction on sidewalls (They’re used on my audi tyres because it’s heavier)
How to work out the tread depth on tyres?
The legal limit on a tyre is 1.6mm. Car tyres are virtually bald when they’re at this point, and offer 0 grip. My tyres currently have about 5mm of tread left (new tyres are normally between 8mm-10mm). I’ve done about 20k miles on them already, so they’re very hard wearing tyres.
In order ot read the depth of the tyre, simply use a tyre depth gauge. I use my MOT approved tyre pressure/tyre depth set to take the readings. Inside the little metal rod into the groove of a tyre and push it down until it becomes flat. then turn the stick and simply see where it lines up for the tread depth. Car tyres also have wear markers on them, when these are reached, they’re the legal limit. The tyre also must be legal limit across the width of the tyre. If the tyre is 10mm all over, but say 1m at the edges. Then the tyre is illegal, not to mention you also most likely have another problem like tracking
Why should you replace a space saver with a full size spare
Spave saver tyres don’t have a high rating, or long distance. They’re meant to be used in an emergency to get you to tyre shops. So you are out of luck if you intend on going long distance somewhere, or getting there quickly. Another more important point to note, is that space saver tyres are normally SMALLER in both width and height of a full size wheel. This is important, because it affects the rolling radius on an Axle which affects not only the handling, but can damage transmission on a vehicle because of the extra load on it and different rotational speed.
If you have a puncture tyre on a Front Wheel Drive vehicle, you would have to swap one of the front wheels for a rear wheel, and then fit the space saver on the rear where the failed tyre would go. So this would cause a lot of extra work, as you have to change two tyres for 1 problem.
Having a full size eliminates this problem, you’re limited by the speed rating of the tyres only, and can continue as normal on your jounrney (albeit with a tyre repair to do) until you get to your destination, or somewhere to repair the spare type.
What is the speed limit on space saver tyres
Space saver tyres, are normally recommended to a maximum speed of 80 km/h or around 50 mph, due to their narrow design, the traction on the road is reduced. So they’re not really designed for high speed driving, nor are they meant to be driven a long distance
What are the benefits of a full size spare tyre
As noted above with space savers, you’re not limited by speed, or tyre size. So you can simply fit the tyres and swap them over and then continue your journey as normal once replaced. Nor do you need to worry about which axle location it is fitted. When you fit a space saver you have to take car on transmission. Swapping tyres on a FWD, or something like a 4WD disconnecting the propshaft. As it’s easy to damage transmission
What are the negatives of a full size spare tyre
The main negative of having a full size spare tyre in your car boot, is the lack of space. Normally if your car has a space saver fitted inside the boot, or worse that stupid slime stuff. Chances are your car boot will be extremely narrow in height, and won’t be able to fit a space saver tyre under the false floor. Now, this isn’t a bad thing, as it doesn’t affect you in any way except you lose some space. My car just gets used for storage and shopping so it doesn’t bother me. So I’ll either need to get a full size spare tyre insert for the boot, which adjusts the height of the boot and utilises different storage space. Or make up some form of false floor, I’d like to keep the car OEM so trying to find boot inserts. If not I’ll most likely knock up a template using wood/MDF. Then use expanding foam to make my own insert. I’d much rather have one made of foam to keep it light, but it gives me back the space without the extra weight
The full size spare is also the weight of a normal alloy/tyre. So it adds a slight bit of weight to your vehicle (maybe an extra 15kg) however for the convenience you get knowing you won’t have to rely on a crappy tyre, for me it’s worth it.
Important notes regarding spare wheels/space saver tyres
- If you have a spare wheel in the car, it will be tested on an MOT, so you car can fail if the spare tyre is less than legal limit. If in doubt remove it from the car, as it’s not a requirement to have one for an MOT
- Space savers fitted to a car will result in an MOT failure
