bagwell

my audi TT has oem 18s that used to be runflats and came with no spare at all just a repair kit. I have seen other TT owners have fashioned an 18" donut spare from a VW R32 but I can't find an 18....would something like this work.... http://cgi.ebay.com/ebaymotors/VW-AU...Q5fAccessories

why or why not?

I can tell you right now my Prius has a 15" spare and I swapped the wheels to the OEM 17s

LiCelsior

iTrader: (32)

if its truely temp then i wouldnt worry about it. just drive slow and get the original rim fixed asap.

Byprodrive

iTrader: (1)

the closer the O.D. the better, watch out for brake clearance. Lots of OEM spacesavers are not exactly the same as the tires. Lexus IS isn't since the front & rear vary about a inch.

PhantomZX

It doesn't have to match unless the sizes are very different and your car has some kind of traction control that believes you have slippage due to the hubs turning at different rates.

You do have to make sure the hub bore, bolt pattern/spacing, and offset will be compatible.

IS-SV

I'm curious what is advised in the TT's manual, especially being AWD.

bagwell

its not a Quattro...FWD only

Lil4X

2WD should be the same diameter on either end of the drive axle, while AWD or 4WD should all be the same - otherwise you are rotating one wheel faster than the other - fine for a short time, but bad for the diff in longer term service. LSD's are particularly picky about wanting to run both wheels at the same speed.

IS-SV

That's an important factor (being fwd vs awd).

bagwell

thanks for the input...

can you define a short time?

are we talking 10-20 miles max before damage or?

...because most likely this would only be used while on a long range trip on open freeway, otherwise I'd just have the flat fixed if local.

Lil4X

I wouldn't want to run that off-size wheel on the ground for more than twenty minutes or so, and that at 50mph or less. That's still a fair amount of wear on a clutch-type LSD, and even worse on an AWD system. Actual damage depends on the difference in diameter and type of diff you have. If you are running a locker on a RWD or a mechanical 4WD, don't worry, the heavy jolts and noises will remind you there is something REALLY wrong back there.

That should still get you to an exit with a decent tire shop. In an emergency, you can probably get your hands on a used or REALLY cheap tire for $30 or so (installed) that's at least the correct diameter. You can throw it away after getting a matching tire, or use it as a tire swing for the kids . . .

pbm317

Your prius 15" vs 17" is probably still the same diameter, the 15" just has a taller sidewall to make up for the 2" of wheel

Infra

iTrader: (1)

Your instruction manual should tell you the time and distance you can keep the spare on there... everyone else here is just guessing.

IS-SV

I suggested the manual in post #5, curious what's advised.