Just got some new uniroyal rainexperts fitted yesterday and they are really good. Nice and grippy, give much better feedback than my old tyres aswell. My only concern is the psi put into them. The fitter from event tyres (fantastic company!) said they need around 32-33 psi. The tyres dont look underinflated to much but I ran my previous tyres at 35 front and 40-45 rear based on their 10% under their max psi markings. They looked like they sat on the road with a full contact patch without squidging which the new tyres do.

Now the rain experts have no indication as to a maximum psi so im a bit lost as to what sort of PSI i should be looking at. I say this because my MPG is down by atleast 5 according to the trip computer which is pretty bad! Almost 10%! Does anyone know what PSI they can take? Bit surprised they have no indication.

Vrs? if they're standard size(205/50-17) the pressures are on to fuel filler flap,40-45psi at the rear didn't that make it a bit loose? Seem a lot of pressure

Your owners manual will give the correct pressures for your car/tyre size.

I've never heard of anyone using the max pressure limits as a basis for tyre pressures! You need to account for the vehicle, load and tyre spec.

It might even say inside the fuel filler cap actually.....

45psi seems very high compared to what you're running in the front. I run 33psi front and 30psi rear (205/50R17).

no its not a vrs! Just a boring diesel on standard 205\55\16.

The front max rated psi was 36 i think and the rear was 51! That was part of the reason i wanted to switch. I know mismatched front to rear tyres is supposed to be okay but i didnt like it and the tyres were **** anyway. I found if i was at 32 the tyres were just to squidy and vague.

If you check half way down this page http://www.carbibles..._bible_pg3.html it explains the 10% 'rule'. I've heard about it in a few places and found my car handled absolutely fine at a little under 10%. The tyres also had no uneven wear and no scrubbing after 6000 miles including a LOT of dry steering due to the terrible parking where I live. Obviously I checked the contact patch and the entire width of the tyre was in contact and had a small bit of deformation in the sidewall.

It just seems odd they dont have a max rated psi!

I've never heard of anyone using the max pressure limits as a basis for tyre pressures! You need to account for the vehicle, load and tyre spec.

Shouldn't you also take into account the tyres maximum pressure then?

The Max - 10% theory sounds like a bad idea to me. I can understand it from the fuel economy perspective but IMO there would be too much of a compromise on ride and more importantly safety. I wouldn't fancy my chances of stopping quickly or having to swerve to avoid something with tyres inflated to that sort of pressure. Using this theory I expect some car/tyre combinations would definitely cause uneven tyre wear. Once the tyre warms up it would get closer to the max limit.

I usually inflate my tyres to somewhere between the unloaded and loaded rates in the fuel cap as I find the unloaded pressures feel a bit soft.

Edited 15 March, 201214 yr by vrsTom

The Max - 10% theory sounds like a bad idea to me. I can understand it from the fuel economy perspective but IMO there would be too much of a compromise on ride and more importantly safety. I wouldn't fancy my chances of stopping quickly or having to swerve to avoid something with tyres inflated to that sort of pressure. Using this theory I expect some car/tyre combinations would definitely cause uneven tyre wear. Once the tyre warms up it would get closer to the max limit.

I usually inflate my tyres to somewhere between the unloaded and loaded rates in the fuel cap as I find the unloaded pressures feel a bit soft.

I'll look in my book for that - its not on my fuel cap. I found today driving at 32psi was very very squidgy and was making a noticeable delay to when the car turned. I also had a look at the tyres and they are definately underinflated because the edges are bulging out.

The guy who said "max - 10%" is talking through his anal oriface. That pressure is guidance for tyre fitters when they're blowing the tyres back onto the beads.

I've had Michelins, Dunlops (I know, but they were there when I bought it) and Toyos on mine, and the Skoda recommendations of 30 front 32 rear are fine for M & D, and about 2PSI soft for T.

sounds very high to me. If you are only interested in MPG then blow those puppies right up :wonder:

Lol mike :-)

Obviously getting good mpg is one factor, but im not going to severely reduce grip just to save a few quid on fuel.

It must be pointed out - for a tyre to be resistant to aqua planning it can't be run at stupid low psi anyway which is what it currently looks like. Maybe i should take a picture of the tyres.

no its not a vrs! Just a boring diesel on standard 205\55\16.

The front max rated psi was 36 i think and the rear was 51! That was part of the reason i wanted to switch. I know mismatched front to rear tyres is supposed to be okay but i didnt like it and the tyres were **** anyway. I found if i was at 32 the tyres were just to squidy and vague.

If you check half way down this page http://www.carbibles..._bible_pg3.html it explains the 10% 'rule'. I've heard about it in a few places and found my car handled absolutely fine at a little under 10%. The tyres also had no uneven wear and no scrubbing after 6000 miles including a LOT of dry steering due to the terrible parking where I live. Obviously I checked the contact patch and the entire width of the tyre was in contact and had a small bit of deformation in the sidewall.

It just seems odd they dont have a max rated psi!

Shouldn't you also take into account the tyres maximum pressure then?

If i ran my tyres that high on pressure i would be off the road, way over inflated for my driving style, and i have same tyre size as you. yes over inflation does help with mpg, always has but not safety you wouldnt have as much rubber on the road for braking. trust me, I had an accident back end of last year and my tyres were 32 all way round. stopped on a dime in the wet after I had hit the motorbike. If i had had pressures at that psi i would have still been sliding and run over the biker who was flung 35ft back the way he had just come from after hitting car on opposite side of road in pouring rain and bouncing into my path going the other way at 30mph.

I always set machine to 33 as u always lose a psi when you take pump off. when under load i add 3 psi to front and 5 to rear.

Every car I have owned weather petrol or that other dirty fuel, 31-32psi front 33-35psi rear.

With an exception to my transit 55 front 70 rear.