Research conducted by German motoring watch-dog DEKRA found that aiming the spray directly at the sidewall can cause tiny, barely detectable holes to appear on the rubber. And according to experts at the UK's leading tyre safety organisation, TyreSafe, with the sidewall weakened, the chance of a blow-out is hugely increased.

The group also warned against using strong detergents. When combined with a high-pressure blast of water, they can remove important protective chemicals from the compound. This damage, which could show up as a brown watermark, reduces both durability and grip.

With more than 80 per cent of drivers apparently unaware of the perils, TyreSafe has issued some potentially life-saving guidelines. Avoiding machines which run at pressures of more than 110 bar is top of the list, but the body also recom­mends using the widest spray pattern.

In addition, it advises owners to keep the washer nozzle at least 20cm from the surface of the tyre when cleaning, and not to aim the jet directly at the join between the tyre and rim. 
" WITH MORE EXTRAS THAN A HOLLYWOOD EPIC "

Hmm... interesting. I wonder how accurate this is?

Not that I'm in any danger of this problem, given me and carwash are mutually exclusive. 

Great- just bought a Karcher with 130 bar pressure to celebrate lifting of hosepipe ban!!! Is this an early April Fool joke?

Those of us serious about detailling (the "wash only in the direction of the airflow" crowd) would never use a high pressure washer on a car. I had a neighbour a few years back who used to wash his Ferrari Maranello 575 with a Karcher power washer....painful to watch.  2006 Range Rover Sport TDV6 HSE, Java/Ebony/Cherry, Privacy, Sunroof, PTI, Premium Sound, SatNav, Cold Climate, Tow kit, CarStyle coded grill and vents, Tasmods, Stormers, JE Exhaust, Autobiography badge

High pressure jet washes can damage paintwork if the nozzle is held too close to the vehicle.

With the new 'water' based paints used in the auto trade a jet wash can do a lot of damage. Arctic Frost TDV6 SE. Aspen Leather, Cherry Wood, Privacy Glass, PTI, Tow Pack, Mudflaps, Tasmods, a new Fuelflap, a RRSport.co.uk umbrella in the boot & a RRSport.co.uk sticker on the rear glass.
__________________

Don't use'em myself = after 1st hand experience of stripping the paint of my 1st 1.9 205 gti back in the 80/90's ....... what was a white car became dull grey below the bumper line  
" WITH MORE EXTRAS THAN A HOLLYWOOD EPIC "

Thanks fellas. I really had no idea about potential damage to paintwork so will ensure the jet is distant in future and not too strong.

TB wrote:

High pressure jet washes can damage paintwork if the nozzle is held too close to the vehicle.

With the new 'water' based paints used in the auto trade a jet wash can do a lot of damage.

today I shall mostly be using my pressure washer on van and cars

Hooligan!!

I know it sounds strange but I was advised to only use a pressure washer on a clean car.

The dirt and grit needs gently washing off first otherwise you are simply sandblasting the paint.

I have happily jetwashed my last 5 cars without any problems. Real Off-roader - Suzuki Jimny (SN413), KAP 3" Lift, KAP Full Roll Cage, ARB Locker, On-board Air, Winch bumpers front and rear, Wrangler MT's, Recaros.

Perhaps I'll take my Karcher back out the box then? I have a "snow" washing detergent that you apply at LOW pressure first, leave for a few minutes, then high pressure off. Maybe I wont kill the car after all?

I've used one of those Karchers for cleaning up the decking in the back garden, but it'd seem to powerful to use on the car's bodywork. It's much higher pressure than the local jetwash... 

Thanks for the advice Shmoogle, I'd best go easy then or I'll probably end up with a naked car wearing only primer???

Which you could say was a custom colour and the be the envy of all your friends!