Omega Owners Forum

Chat Area => General Discussion Area => Topic started by: SP_3.2 on 29 August 2007, 10:26:46

Title: Tyre pressure and full rev range
Post by: SP_3.2 on 29 August 2007, 10:26:46
Just wondering what pressures you lot run your tyres at the book says for 235 is 31 psi i have seen that some have there's higher are there any avantages to this?.

Also I tend to drive the car without opening her up much . Just how often should I take her tp full rev range and use sport,s to keep the enging in good shape


Thanks Guys
Title: Re: Tyre pressure and full rev range
Post by: TheBoy on 29 August 2007, 10:31:30
I tend to run my MV6 (prefacelift) 32 at rear, 35 at front  (38F/45R heavy load).

I'm never shy when it comes to 'exercising' the motor ::)
Title: Re: Tyre pressure and full rev range
Post by: IrmscherKris on 29 August 2007, 10:31:54
I run my 235's at 34PSI front and rear.

The odd blast every now and again will keep it tip top.


 :y
Title: Re: Tyre pressure and full rev range
Post by: Kevin Wood on 29 August 2007, 10:49:50
My rear 235s were showing signs of overinflation when I changed them recently (down to TWI in the middle, 4mm at the oustide edges!). During most of their wear I didn't own the car but there is not huge weight over the rears with an empty boot (and a lot of weight with a full boot and back seat) so it would probably be more prudent to adjust the rear tyre pressures according to load (although it's easy to forget). I was running mine at 34 but am going to reduce the rears to 31 and see how that goes.

Fronts should see less load variation due to them supporting a cast iron V6 all the time!

I don't think the mythical "italian tune-up" is necessary not does it make much difference how an engine is driven once it's run in, but if you've got it, you might as well use it every so often!

As long as it is serviced regularly (more so than the manufacturer's recommendations!), ideally doesn't spend all its' life on shopping trips but gets a few long motorway journeys, and, most important of all, isn't ragged from cold it should be fine.

Kevin
Title: Re: Tyre pressure and full rev range
Post by: TheBoy on 29 August 2007, 10:52:49
Quote
My rear 235s were showing signs of overinflation when I changed them recently (down to TWI in the middle, 4mm at the oustide edges!). During most of their wear I didn't own the car but there is not huge weight over the rears with an empty boot (and a lot of weight with a full boot and back seat) so it would probably be more prudent to adjust the rear tyre pressures according to load (although it's easy to forget). I was running mine at 34 but am going to reduce the rears to 31 and see how that goes.

Fronts should see less load variation due to them supporting a cast iron V6 all the time!

I don't think the mythical "italian tune-up" is necessary not does it make much difference how an engine is driven once it's run in, but if you've got it, you might as well use it every so often!

As long as it is serviced regularly (more so than the manufacturer's recommendations!), ideally doesn't spend all its' life on shopping trips but gets a few long motorway journeys, and, most important of all, isn't ragged from cold it should be fine.

Kevin
Reason I run fronts harder than spec was to even out the wear - even at the recommended 32PSI, the middle was wearing less than the edges...
Title: Re: Tyre pressure and full rev range
Post by: IrmscherKris on 29 August 2007, 11:06:56
Quote
I don't think the mythical "italian tune-up" is necessary not does it make much difference how an engine is driven once it's run in, but if you've got it, you might as well use it every so often!

I'd have to disagree with you on that, any car I've bought off people who don't thrash seem to feel locked (if that makes sense?). After a few good sympathetic beatings they feel.... nice and loose (ish).

You seem to get better MPG IMO from doing this too.
Title: Re: Tyre pressure and full rev range
Post by: TheBoy on 29 August 2007, 11:09:03
Tunnie commented that his 2.2 seems 'a bit freer' after I gave it a good ragging trying to keep up with his 2.5 Elite he bought from Ronnie McB ::)
Title: Re: Tyre pressure and full rev range
Post by: bob.dent on 29 August 2007, 11:26:16
I have 235/40/17's on the front and 265/40/17's on the rear and I had been running mine at slightly lower pressures since I had new tyres put on as the previous tyres (rears) had shown signs of over inflation by wearing in the middle. Big Rod (the previous owner) said he had normally run them at 30psi all round, so I've been running them at 28psi.
Since then I noticed my mpg reduced to around 22 on average to and from work. I checked my pressures last night and they were slightly down on the original 28psi I put in a few weeks ago, so thought I'd try them back at 30psi as these tyres are a slightly softer compound than the last set. I reset my MID this morning and was amazed that after my 22 mile journey to work my average mpg had gone up to over 25.

It will be interesting to see what average mpg I get going to Newent this weekend. :-?
Title: Re: Tyre pressure and full rev range
Post by: TheBoy on 29 August 2007, 11:30:11
After the lakes, I kept forgetting to reduce pressure, so 38F/45R for about 2 weeks. MPG went right up.  Ride comfort and handling were compromised though...
Title: Re: Tyre pressure and full rev range
Post by: Markjay on 29 August 2007, 11:39:01
33psi all around, I always put the pressure up from the manufacturer's recommendation by 2-3psi for a slightly more sporty ride.

As for the rev range, my understanding is that this is important when the engine is being run-in i.e. when new or after a rebuild, not sure it will make any difference to a 'broken-in' engine i.e. with 20k-30k miles or more.



Title: Re: Tyre pressure and full rev range
Post by: Tony H on 29 August 2007, 15:41:45
Whilst on the subject of revs does anyone know at what speed a 2.5 auto in sport mode should change from 3rd to 4th?
The reason I ask is last week I had a run along our local air strip ;) stretching the Meegas legs and noticed it change up into 4th at 120 mph,I didn't look at the rev counter but have the feeling it wasn't at the blood line.
I used to own a Granada that would do its top speed in 3rd as well as 4th :-/
Title: Re: Tyre pressure and full rev range
Post by: Kevin Wood on 29 August 2007, 15:47:55
My 3.2 changes up from 3rd to 4th early if not in sport mode and absolutely floored.

I can't recall what speed. I'm always too busy looking for coppers the braking point for the next corner of my private test track. It wouldn't be much more than 120 and, given that the 2.5 is shorter geared that's probably not far off the red line.

Kevin
Title: Re: Tyre pressure and full rev range
Post by: TheBoy on 29 August 2007, 16:09:09
My earlier software would not change into 4th in sports mode - just carry on down the road track banging off the limiter at 130mph.

Believe it or not, not tried since updating firmware...
Title: Re: Tyre pressure and full rev range
Post by: Taxi_Driver on 29 August 2007, 18:30:10
Quote
I have 235/40/17's on the front and 265/40/17's on the rear and I had been running mine at slightly lower pressures since I had new tyres put on as the previous tyres (rears) had shown signs of over inflation by wearing in the middle. Big Rod (the previous owner) said he had normally run them at 30psi all round, so I've been running them at 28psi.
Since then I noticed my mpg reduced to around 22 on average to and from work. I checked my pressures last night and they were slightly down on the original 28psi I put in a few weeks ago, so thought I'd try them back at 30psi as these tyres are a slightly softer compound than the last set. I reset my MID this morning and was amazed that after my 22 mile journey to work my average mpg had gone up to over 25.

It will be interesting to see what average mpg I get going to Newent this weekend. :-?

Dont forget tho Bob......the rears should be 3psi higher than the fronts on estates.....i assume that applies for your 265's as well.

I run my 225's 30 front and 33 back  :y

Tho my tyres take abuse......coz one min it can be just me in it......10mins later 4 15 stone passengers  ;D  

I did once inflate to 33 front 36 back as a comprimise.......but overinflation wear started showing after a time.


Title: Re: Tyre pressure and full rev range
Post by: bob.dent on 29 August 2007, 18:39:59
Quote
Quote
I have 235/40/17's on the front and 265/40/17's on the rear and I had been running mine at slightly lower pressures since I had new tyres put on as the previous tyres (rears) had shown signs of over inflation by wearing in the middle. Big Rod (the previous owner) said he had normally run them at 30psi all round, so I've been running them at 28psi.
Since then I noticed my mpg reduced to around 22 on average to and from work. I checked my pressures last night and they were slightly down on the original 28psi I put in a few weeks ago, so thought I'd try them back at 30psi as these tyres are a slightly softer compound than the last set. I reset my MID this morning and was amazed that after my 22 mile journey to work my average mpg had gone up to over 25.

It will be interesting to see what average mpg I get going to Newent this weekend. :-?

Dont forget tho Bob......the rears should be 3psi higher than the fronts on estates.....i assume that applies for your 265's as well.

I run my 225's 30 front and 33 back  :y

Tho my tyres take abuse......coz one min it can be just me in it......10mins later 4 15 stone passengers  ;D  

I did once inflate to 33 front 36 back as a comprimise.......but overinflation wear started showing after a time.

With normal wheels and tyres I'd agree Dave, but the tyres that came off the rear were worn in the middle which would indicate over inflation. I'm going to see Tony at WIM tomorrow so I'll see what he recommends.
Title: Re: Tyre pressure and full rev range
Post by: Jay w on 29 August 2007, 20:23:51
i regularly introduce the rev needle to the redline, i has got to be done  :y

Title: Re: Tyre pressure and full rev range
Post by: cem_devecioglu on 29 August 2007, 20:31:26
Winter tyres 32 front 30 back..

Normal tires 30 front 28 back... Long journeys  29 front  28 back (summer)

tried 225 km/h..if the measurement is OK.
Title: Re: Tyre pressure and full rev range
Post by: Kevin Wood on 29 August 2007, 22:32:10
Quote
Quote
Quote
I have 235/40/17's on the front and 265/40/17's on the rear and I had been running mine at slightly lower pressures since I had new tyres put on as the previous tyres (rears) had shown signs of over inflation by wearing in the middle. Big Rod (the previous owner) said he had normally run them at 30psi all round, so I've been running them at 28psi.
Since then I noticed my mpg reduced to around 22 on average to and from work. I checked my pressures last night and they were slightly down on the original 28psi I put in a few weeks ago, so thought I'd try them back at 30psi as these tyres are a slightly softer compound than the last set. I reset my MID this morning and was amazed that after my 22 mile journey to work my average mpg had gone up to over 25.

It will be interesting to see what average mpg I get going to Newent this weekend. :-?

Dont forget tho Bob......the rears should be 3psi higher than the fronts on estates.....i assume that applies for your 265's as well.

I run my 225's 30 front and 33 back  :y

Tho my tyres take abuse......coz one min it can be just me in it......10mins later 4 15 stone passengers  ;D  

I did once inflate to 33 front 36 back as a comprimise.......but overinflation wear started showing after a time.

With normal wheels and tyres I'd agree Dave, but the tyres that came off the rear were worn in the middle which would indicate over inflation. I'm going to see Tony at WIM tomorrow so I'll see what he recommends.

True. Change the tyre size and the contact patch changes in area so the pressure required will be totally different and it's best to experiment. With those hoofing great tyres on the rear I suspect the ideal pressure will be quite a bit lower on the back than the book pressure. It all depends, for each wheel, on the weight it's carrying against the area of the contact patch.

Taking the extreme example I've got 205/50/15s on my Westfield, which weighs in a tonne less than an Omega and I reckon about 17-18 PSI all round is the best pressure. I had to experiment a bit to arrive there. Putting more air in makes it feel quite taught and responsive at first, and you can go quite high on pressure with no ill effects but you realise that there's less grip if you push it, and tyre wear will eventually confirm it. If you go a pound or two under the ideal, it quickly gets a bit vague and tends to let go when pushed.

Kevin
Title: Re: Tyre pressure and full rev range
Post by: familyman on 29 August 2007, 22:56:04
Does anyone other than me use bar instead of psi or am i getting to modern ;D ;D ;D
Title: Re: Tyre pressure and full rev range
Post by: Kevin Wood on 29 August 2007, 23:01:04
Quote
Does anyone other than me use bar instead of psi or am i getting to modern ;D ;D ;D

Always used PSI for tyres and, although I'd use bar when talking about most other things I haven't got a clue what a sensible tyre pressure in bar would be :-/

Kevin
Title: Re: Tyre pressure and full rev range
Post by: CaptainZok on 29 August 2007, 23:06:43
Quote
Quote
Does anyone other than me use bar instead of psi or am i getting to modern ;D ;D ;D

Always used PSI for tyres and, although I'd use bar when talking about most other things I haven't got a clue what a sensible tyre pressure in bar would be :-/

Kevin

Ask Spongebob he's the baa expert.  ;D
Title: Re: Tyre pressure and full rev range
Post by: TheBoy on 30 August 2007, 08:01:19
Quote
Does anyone other than me use bar instead of psi or am i getting to modern ;D ;D ;D
I use mm etc rather than the rubbish that the old timers use  :P, but still use PSI - 32PSI seems better than 2.1bar (or whatever it is)...
Title: Re: Tyre pressure and full rev range
Post by: omegaman2 on 30 August 2007, 15:21:27
after holiday season i did not put pressures down  ( lazy ) 36f 42b for caravan, the ride was harsh and back tires were worn down to limit in middle but 000;s miles left side treads ...anyway 4 corners replaced and tyre man put 36 in each not to bad but i reduced to 30 allround and now have magic carpet ride smooth & quiet :y
Title: Re: Tyre pressure and full rev range
Post by: cem_devecioglu on 31 August 2007, 00:59:55
Does anybody use here nitrogen..Think it better than air
Title: Re: Tyre pressure and full rev range
Post by: Kevin Wood on 31 August 2007, 09:33:07
Quote
Does anybody use here nitrogen..Think it better than air

Never tried it although my local tyre depot has a sign up saying they'll use it on request (for a fee).

Because it contains no water vapour the tyre pressure remains much more stable over a wide range of temperatures. Not sure tyre pressure is that critical on an Omega, nore does tyre temperature really vary over such a great range but it's useful in motorsport where you'll always be chasing the right tyre pressure and getting serious heat into the tyres at the same time.

I remember watching a documentary on a Le Mans team in the run-up to the 24h and they were chasing all sorts of suspension setup problems until someone noticed that the tyre pressures had gone to pot after a fast run. Turns out the tyre fitter had put moist air into the tyres.

Kevin
Title: Re: Tyre pressure and full rev range
Post by: cem_devecioglu on 31 August 2007, 13:22:33
Quote
Quote
Does anybody use here nitrogen..Think it better than air

Never tried it although my local tyre depot has a sign up saying they'll use it on request (for a fee).

Because it contains no water vapour the tyre pressure remains much more stable over a wide range of temperatures. Not sure tyre pressure is that critical on an Omega, nore does tyre temperature really vary over such a great range but it's useful in motorsport where you'll always be chasing the right tyre pressure and getting serious heat into the tyres at the same time.

I remember watching a documentary on a Le Mans team in the run-up to the 24h and they were chasing all sorts of suspension setup problems until someone noticed that the tyre pressures had gone to pot after a fast run. Turns out the tyre fitter had put moist air into the tyres.

Kevin

Yep.Nitrogen is not effected by temperature changes like normail air..And I feel its more comfortable than air..Here the temperature changes in night and day and driving conditions change the tires for higher pressures and make the omega jump jump  :)
Title: Re: Tyre pressure and full rev range
Post by: Crazydad on 31 August 2007, 14:54:03
Up to now i have allways used nitrogen in all my vehicles, but the Omega has such a smoooooth ride that i

don`t find it necessary.

The only thing is i have to check my pressures more often, 2,3 bar all round low mpg nice ride
Title: Re: Tyre pressure and full rev range
Post by: Kevin Wood on 31 August 2007, 15:38:11
Interesting. I never knew it influenced ride quality. Maybe I'll try it next time.

Kevin
Title: Re: Tyre pressure and full rev range
Post by: SP_3.2 on 31 August 2007, 15:59:34
Any thing to keep the MPG on the right side. How much is 2-3 bar in PSI?.

Thanks.  
Title: Re: Tyre pressure and full rev range
Post by: cem_devecioglu on 31 August 2007, 22:32:37
nearly 33.36 psi =2.3 bar