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[feeutfo]

and just to muddle things up further. Load rating may not stay the same if you change the tyre size. ie 265/40/17 453's are 100 rated. What a mess

So the 100 rated tyre tram lines less? On the LC ? Do I have that right?

[SMD]

  Hmm...

Just got back from an hour long drive on various types of roads, drove into ruts etc and trying to induce tramlining but nada.

There is one road in particular that is nasty for tramlining, car felt a bit unsteady but didn't tramline much. Although this could be because I got caught behind slower moving traffic both times so wasnt going as fast as I normally would.

Pressures 32psi all round.

Might drop it to 28psi all round tomorrow as TB suggested and see how it behaves

[feeutfo]

Thank god for that. Glad your sorted.

So top of the scale could be 97xl at 34psi in oe 17 size. Enough to
Put the that Eagle f1 out of the sweet spot for the omega.

Or so SMD's ecperience might imply...?


Just purely as sn an Example. The other end of the scale might be An Eagle f1 with a 94 or 93 rating that needs to be above 34psi. Eg if the load rating is between those extremes the car should behave itself, on the eagle f1.


Wonder if Opti fancys playing with his pressures...? Do I recall he has 94 load..?

[feeutfo]

Although, wouldn't want the tyre to over heat Opti.

[SMD]

The only changes between now and before are:

1. I went to WIM and although Tony couldn't find anything that would cause tramlining, small adjustments were made. I dont know what exactly because I was distracted by the leaking oil sump.

2. I bought a dedicated tyre pressure gauge and set all tyres to 32psi to within an accuracy of 0.5psi. Previously I used a footpump with a built in gauge

[Lazydocker]

The only changes between now and before are:

1. I went to WIM and although Tony couldn't find anything that would cause tramlining, small adjustments were made. I dont know what exactly because I was distracted by the leaking oil sump.

2. I bought a dedicated tyre pressure gauge and set all tyres to 32psi to within an accuracy of 0.5psi. Previously I used a footpump with a built in gauge

And that could well be the required change

Although garage air lines aren't accurate either they tend to be consistent which foot pump gauges generally aren't

[feeutfo]

While the digital pressure gauges may or may not need calibrating, as dbug so eloquently suggests, a neighbour here had one calibrated at fair expense, and the two digital gauges we had to hand including mine, where perfectly accurate when compared.
More so than some of the cheap air tool pressure gauges and garage forecourt  gauges .

Ime on the tyres I've had, 28 - 34psi range is enough to discover if pressure affects the way the tire tracks. You can go higher or lower, but any more and it gets dodgy on ride and concerns over dinged rims come into play.

I've just dropped my front ao1 to 28 to see of it makes any odds. It doesn't. I'll try 34 tomorrow.

[feeutfo]

Should add, opposite to yours SMD. I felt the rear of mine have a little wander yesterday. Checked the pressures, down to 28.5 from 32psi on one side.

Hope its not a slow puncture or sumat stuck in the tyre. 265/35/19 ain't cheap.

Might have been the low psi, but they are also half worn now, so it might be that.

[SMD]

This worries me too now that I spent £500+ on tyres. When I bought this car it had Eagle F1s on the rear axle. Every week it lost a bar pressure due to slash on the inside sidewall on one tyre.

Tyres for my humble 17" rims cost £130 a pop for decent ones. Still there's part worns if you can't afford another sport conti Chris. I paid £30 for my sportconti2 last year 

[feeutfo]

This worries me too now that I spent £500+ on tyres. When I bought this car it had Eagle F1s on the rear axle. Every week it lost a bar pressure due to slash on the inside sidewall on one tyre.

Tyres for my humble 17" rims cost £130 a pop for decent ones. Still there's part worns if you can't afford another sport conti Chris. I paid £30 for my sportconti2 last year 

I don't want to start you know who off, but part worns, IMO, have a place for experimentation or for getting out of a tight spot... ...or for destroying on an airfield ...although I have a few here that I'll be glad to see the back of.

[2woody]

my experience with load ratings is that they have little to do with the construction of a tyre.

in many conversations with many tyre manufacturers it appears that they design the tyre with a target weight of vehicle in mind and post the load rating to suit, rather than design the tyre around an absolute load/speed index rating. Every time I've contacted them for a chat about running a vehicle above the load ratings, they've come back and said yes its fine, here's a letter allowing manufacturer "x" to run this vehicle at that weight on our tyres, "Y" kg above the load/speed index.

I've had permissions to run vehicles maybe 500kg above the labelled ratings before now, which leads me to believe the rating has little to do with the construction.

[dbug]

my experience with load ratings is that they have little to do with the construction of a tyre.

in many conversations with many tyre manufacturers it appears that they design the tyre with a target weight of vehicle in mind and post the load rating to suit, rather than design the tyre around an absolute load/speed index rating. Every time I've contacted them for a chat about running a vehicle above the load ratings, they've come back and said yes its fine, here's a letter allowing manufacturer "x" to run this vehicle at that weight on our tyres, "Y" kg above the load/speed index.

I've had permissions to run vehicles maybe 500kg above the labelled ratings before now, which leads me to believe the rating has little to do with the construction.

Have a read of this mate - its the British Tyre Manufacturers’ Association Tyre Technical Advisory Committees report on Replacing Car Tyres, together with legal implications re "service description", which includes speed rating and load rating or index.  http://www.btmauk.com/data/files/Replacing_Car_Tyres_1_June_2011.pdf 

[feeutfo]

Early days and might be wishful thinking, but there appears to be some relevance to higher load ratings being more suitable.  Well, in my mind anyway.

[2woody]

Have a read of this mate - its the British Tyre Manufacturers’ Association Tyre Technical Advisory Committees report on Replacing Car Tyres, together with legal implications re "service description", which includes speed rating and load rating or index.  http://www.btmauk.com/data/files/Replacing_Car_Tyres_1_June_2011.pdf 

will do ! thanks.

I've only ever done this as a motor manufacturer getting specific permission from the tyre manufacturer to run outside the load/speed index on new vehicles.

all read now - and good stuff as an "aide-memoir" for tyre fitters, etc.

full of "may be illegal", too

its because of this sort of stuff that I've approached the manufacturers for specific permission. It would all be easier if I could tell you the circumstances, etc.

[feeutfo]

Lifted from another thread. Thanks to D.

Standard 17 Elite alloys on 3.2 Elite with LPG. GY F1 assym 2 XL

Cannot really complain except for the fact that they are quite noisy, esp over poorer surfaces. About 6k on them so far. No experience in the size you ask for though, so may be useless to you.

Could you post the size, speed and load ratings D, if you get a mo.

17" std elite alloys, so 235/45/17, XL 97 Y.

Edit: To confuse things, there is a F1 assym and a F1 assym 2 (i.e. 2 being the newer version).