Tyre pressures

[graeme thompson]

I know what the correct pressures are for 215/50/15 but is anyone running different sizes and what pressures are they using. I've got 205/50/15 Toyos up front and 225/50/15 rears and I'm sure they are over inflated as the ride seems much harder than on the old Goodyears. Any thoughts would be appreciated. Cheers,Graeme

[chrisw2811]

I run Kumho 205/50/15s all round at 26PSI. 28 PSI gives a harsher ride and below 24PSI will stress the sidewalls. 26 PSI seems to give a reasonably comfortable ride.

[Lotus-e-Clan]

Well if they are Toyo T1Rs then you should definitely try 22 psi! T1Rs have quite rigid side walls to cope with heavy modern bloats and give sharper turn-in.

I ran 24psi all round at first but I found my 205/50/15 T1Rs (all round) too harsh, then I read a bit more about side wall construction and it seemed sensible to reduce tyre pressures as my Excel is much lighter than most moderns using these particular Toyos (my SE has no A/c or PAS and a it's smidge less than 1100kg)

You will probably find most wide modern tyres will have a side wall construction to cope with modern bloats so both your 205 and 225s may need a pressure reduction.... and in any case the wider the tyre the less pressure required for a given kerb weight and tyre contruction so the 225s on the rear especially may need thinking about.

Personally I don't like the idea of mixed widths on an Excel which has pretty even weight distribution, mid or rear engine cars yes, but light weight front engined cars, no.

A few years ago when I drove the Excel without a spare in the boot (in attempt to lose even more weight!) I found the rear far too light and it broke traction far too easily in the wet at roundabouts so the spare went back in!

Similarly, even without a rear weight reduction, with wider tyres on the rear (and therefore less potential grip / square inch of contact area) you would experience too much difference between wet and dry grip unless the compound is particularly soft and sticky.

[barker_001]

Avon ZV3s, 205/15/50, at 26 psi - seems to give a good compromise between roadholding and ride...

[graeme thompson]

Cheers guys, checked the pressures over the weekend, fronts were okay at 24psi but the rears were 30! No wonder it's been a bit bumpy. Lowered to 24psi and will see how it feels tomorrow.
Regards,Graeme

[Ozzy_UK]

running 215/50/15 R888's, run 23PSI all round on track days (cold), and 26PSI (cold) winter (and drive like a total pansy), 24PSI cold summer....
Oz.