I just got a fright... It was time to replace the brake fluid in my Golf, so I whipped off one of the back wheels and saw something that really didn't make my day... The tire was badly deformed and bulging.
I've been using 40psi all round for some time, and this may not have been the only factor as both my back tires were made in 2003 - yes, I know we shouldn't use them for more than 5 years - but they looked like new and had at least 50% of the tread left after 67 000 miles.
Needless to say I went back to 20psi - at least until I can get new replacements - and the deformation became a lot less evident.
These are Michelin Energy Savers BTW size 195/65R15 - I'm ordering some new ones right now...