Space Saver
 

Gents,

This has probably been gone over many times before but I cannot quite find the answer I wanted.

I have an S8 D2 FL with the 20" wheels.

I have a couple of spares but also an LPG tank taking up the spare wheel spot. I could carry a wheel in a bag in the boot but that takes up hell of a lot of space. I of course carry foam, repair kits and a compressor but wanted to look at a space saver.

Yes I know they are limited, but the thought of having one to get me 10 miles to a Kwik Fit etc is a comforting one.

Therefore would the following be suitable:

http://www.ebay.co.uk/itm/AUDI-19-SP...item2ed9f1c044

you need to check that the overall diameter/rolling radius of the spare is within 1% of the other wheels to make sure you dont get any ESP faults thrown up by the quattro getting confused and thinking that the wheels are slipping

That's going to be too small, maybe by about 3% or so. Edit 4.4%!

I had a similar LPG system/tank on an A8 I owned a few years back and I considered space-savers, compressors, foam cans, etc. In the end I opted for not bothering with any of them. Drove it like that for 3 years and never an incident.

Ask yourself, how often have you had a tyre that has deflated so quickly while driving that you couldn't make it home or to the nearest garage. I know in my 25+ years of driving, the answer is never. And, even if it did happen, as long as you've got AA or RAC cover, you can always call them out to deal with it.

If you're like me, and you check your tyres daily, it's unlikely you'll ever get caught out. Better still, get a TPMS and you'll have an early warning of any slow punctures, even while driving. I bought one of these systems a few months ago ... one of the best things I've ever bought. I didn't like the idea of external/dust-cap sensors at first, because I was concerned about throwing the wheel balance off. So I bought some accurate digital scales, weighed them (13-15g) and stuck some additional weights on, directly opposite the sensors and they've been great. Not a single problem or bit of vibration.

Edit: Wrong link. I bought the TP-8886 DIY Tyre Pressure Monitoring System For Android

^ this ^

Just make sure you have decent breakdown cover, who wants to change a punctured wheel at the side of the road anyway?

Me! Beats waiting for hours for a breakdown truck and it's only a 10 minute job. If it's not too flat, limp it to a lay by or petrol station to be safer.

I agree.

Also there must be more than a few mm tolerance on diameter say 2% or so as the electronics must account for a new vs worn tyre that is going to be the case on a car.

Put the spare on with say 2mm tread vs in the extreme case a new tyre on other axel with 7mm of tread.

That looks good moltuae, but what does the display that plugs into the cigarette lighter look like. They show no photos of it. I was thinking of one of these......

http://www.tyrepal.co.uk/products/tb...r-5-wheel-tpms

Mine have only ever tended to be flat at the bottom :D

On the first link moltuae provides, there is a Flash image down the right hand side. If you hover over the different options, it will show what happens on the plug, as well as the associated beeps. Hovering over the wheels of the car shows what happens as well.

There's actually a photo of it on the product page, under the main picture on the left. At least for me there is anyway.

This is the fag lighter plug: http://i.imgur.com/eAruqT0.jpg

And these are the dust cap sensors: http://i.imgur.com/jm5EXD9.jpg

The plug works regardless of whether you've connected to it using the smartphone app. When all is well, and it can see all 4 sensors, the tyre symbol illuminates in green. If there's a problem, it changes colour and bleeps, so you can just plug it in and forget about it. I've plugged mine into the rear fag lighter socket.

The plug will warn you if your tyre pressures or temperatures go out of the desired range (or if it detects a slow/fast leak too, I believe), but you can check your tyre pressures and temperatures any time too just by opening the app (within bluetooth range of course).

There's a few minor quirks, like the 'Engrish' way in which the app ask you "Whether out of program" when you try to exit it, but generally the hardware is of very good quality. I've been using the system now for about 3 months, without any problems.

Having to remove the dustcap sensors to inflate the tyres is a slight inconvenience, since you need to loosen a locking nut on the back before unscrewing them. You could install them without the locking nuts I guess, but the nuts make them more difficult to lose/steal. The thing is though, with the sensors fitted, you'll rarely need to remove them. Before I fitted the system, I used to unscrew my dustcaps every few days to check my tyre pressures, now I no longer need to.

I did look at a few other systems before I bought the SteelMate one, including the one you linked to, but I didn't want to spoil my dash with an ugly aftermarket display unit.