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Just had a puncture fixed, been driving about on the space saver wheel of shame before I put it away I thought I should make sure the pressure is right for the inevitable next time.
The recommended pressure is 60PSI now its off the car it's 26PSI, now i never measured it while it was on the car so I don't know if it was soft while driving on it.
Will the weight of the car force the pressure up in the tyre or is it the same pressure regardless.
Yes it will, but not by that much..
Probably rust around the inside of the wheel rim allowing air to escape.
How long were you driving round on it???
Most of those space savers have restricted speeds and distance to be driven as they have minimal tread.
Drove maybe 18 miles work and back 40mph max, no rust on it seems good condition. Maybe its punctured as well didn't seem soft when it was on though.
60 PSI for a car tyre sounds incredibly high compared to when I last drove over five years ago, back then ~28-35 PSI was common.
Space savers are tiny so need high pressures - think weight of car per wheel, that weight needs to be supported by contact patch x psi.
Yeh think mountain bike tyre vs road bike tyre pressure, less than 30psi vs around 100, its not just grip/comfort, the road bike tyre needs more pressure to support the weight.
So a space saver you'd need a lot more pressure than a regular tyre of around 30psi.
Space savers are designed as emergency 'get me to a garage/home' tyres, as said they don't grip well and thier skinnyness makes for very unpredictable handeling, most are not supposed to exceed 50mph.
Another problem with space savers is they are rarely checked on service, bar for their physical presence. No tech Ive ever met or worked with wants too have to dig past dirty gym clothes, mouldy food, knickers (Yes!), Little 'uns pushchair etc to get to it when you've had to spend 15 minutes hunting for the locking wheel nut key. 60 - 80 psi is about correct for the average. OP should think himself lucky that some bean counter somewhere hadn't decided he'd be better of with a can of puncture jizz and a woeful compressor! 😀