Tyre placard

[sean c]

Can someone please clarify the load ratings on the tyre placard on drivers side door of my MY10 D4 3.0lt.
I currently have 19" tyres and am changing to 18" and thought I would double check before I buy new tyres. The FAQ states minimum load rating for the D4 is 109. Looking at the placard it has different load ratings for different sized tyres. 17"= 111, 18"= 112, 19"= 111, 20"= 109.
Why would there be different load ratings for different sized tyres? Aren't they all carrying the same vehicle mass?
Queensland regulations state;
'Load ratings of tyres must be at least equal to those specified by the manufacturer on the tyre placard fitted to vehicles made after 1972.'
I am concerned a tyre company may interperet this to mean minimum 112 load rating for 18" tyres on this vehicle.
Would appreciate clarification, thanks.
sean

[streetlander]

Tyre manufacturers make tyres for a wide range of vehicles - not just for one make or model.

It is up to you, the vehicle owner, and then the tyre retailer, to match the best suited tyre to your vehicle, given the vehicle manufacturers specifications.

I used to work for a commercial national tyre company, as a store manger, over a decade ago, and there was still confusion back then over load ratings.

All tyres have load ratings, speed ratings, and pressure ratings imprinted/moulded on the sidewall, the tyre staff only have that information to go by. If you wish to have specialised tyres fitted, it will be at your own risk, and they should tell you that!

I have refused, in the past, to fit 4x4 tyres bought in by customers when I, or my staff, were hesistant about fitting them on the vehicle. I have also refused to sell or fit tyres that customers picked out from the rack as they were not suited for their vehicles either.

Most good tyre stores will look at your placard and make suggestions, they should ask how you use your vehicle (ie 80% off road, 20% on road etc) and make recommendations from there.

I must say though I'm a liitle confused about the 'minimum tyre load' most tyres have a 'maximum tyre load' ( ie max load XXXkgs @ XX psi ) - but I have been out of the loop for a while.

[Graeme]

My guess is that the load ratings were the highest available for the particular sizes in their chosen brands when LR did the tyre specs.

[Blknight.aus]

I bet...

that placard print is for more than one spec vehicle and that the rim/profile spec is not backwards compatable.

so if your vehicle comes with 19 inch rims it cant have the 18's fitted and therefore cant carry the weight of the vehicle with the 18 inch rims.


the tyre spec thats preceded with a T as near as I can work out is either a winter spec tyre or a space saver spare, fitting this also requires attaching a sticker to the windshield that clearly advises of the lower speed rating.

[Graeme]

so if your vehicle comes with 19 inch rims it cant have the 18's fitted and therefore cant carry the weight of the vehicle with the 18 inch rims.Not for the D4 because 19" are optional on the 2.7.

[rmp]

An interesting point. The D3 placard had a similar listing but also a blanket statement to the effect that the minimum was 109. The tyres specified were much the same from memory. See if there's any other sub-placard anywhere else.

The Victorian law says the tyres load rating must be at least the '...minimum ratings shown on the tyre placard'. Given they used plural that implies there are multiple ratings, as indeed there are now for the D4. Suspect that is the same for other states. Land Rover also modified the placard from the D3, and it is possible they intentionally omitted the D3's cover-all statement.

So, if you want to stick to the letter of the law there are indeed different load ratings for different tyres for the D4, an interesting point I hadn't noticed. Not logical as you point out - the GVM doesn't change - but we're talking about the law here not logic.

streetlander - what we're talking about here is the minimum load spec for a vehicle, which is always a minimum, eg no fitting 108 tyres to a D3. The maximum load is for the tyre itself.

In the case of offroad tyres meeting minimum load rating isn't usually an issue.

[gghaggis]

The placard shows a multiple of ratings for various combinations of size. I think RMP is on the money in that the minimum of any of those ratings is the minimum allowed. Bolstering that idea is the fact that the ratings are not just for a particular rim diameter, but a complete size specification, eg 255/60R18.

So if you fit a 265/60R18, that specific size is not specified, so one would have to look at the overall minimum. Note that the LR rims are rated to 940kg, which would equate to a 106 for a tyre, + some minimum safety margin.

Regardless, there are several 255/60R18's at 112 loading - Pirelli ATR, Conti AT, GG AT2.



Cheers,

Gordon

[101RRS]

Gordon - didn't you previously indicate the normal 18" rims will not fit a D4 3.0 and that was one of the reasons you got the special order of 18" rims for the D4.

So is the OP putting your rims on or other 18" rims that most likely will not fit.

Garry

[gghaggis]

The placard is a generic one for all D4's - 2.7, 3.0 and 5.0 - so it must cover all rim sizes available for all models. The 3.0 and 5.0 won't fit 17's or 18's, hence my customised 18" rims, which the OP has purchased along with 12 or so others, mostly from this forum.

Cheers,

Gordon

[streetlander]

streetlander - what we're talking about here is the minimum load spec for a vehicle, which is always a minimum, eg no fitting 108 tyres to a D3. The maximum load is for the tyre itself.

In the case of offroad tyres meeting minimum load rating isn't usually an issue.

Thanks for that - was a bit confused!

[sean c]

Thanks for replies all. I have purchased Gordon's 18" wheels and was planning on fitting 265/60R/18 tyres. This size is not on the placard and for me the placard makes no sense stating different load ratings for the same vehicle.
Reading through the replies there is enough doubt for me to ask the regulator for an interpretation of what the minimum load rating should be.
Logically it should be 109 as this is the minimum on the placard and the vehicle mass does not change with different wheel size.
Will advise when I get a reply from Qld government department responsible.
The other way I was thinking, if I get no sensible, response is to get an Engineer to sign off on change. Any thoughts on how this might go?
Sean

[petera]

Thanks for replies all. I have purchased Gordon's 18" wheels and was planning on fitting 265/60R/18 tyres. This size is not on the placard and for me the placard makes no sense stating different load ratings for the same vehicle.
Reading through the replies there is enough doubt for me to ask the regulator for an interpretation of what the minimum load rating should be.
Logically it should be 109 as this is the minimum on the placard and the vehicle mass does not change with different wheel size.
Will advise when I get a reply from Qld government department responsible.
The other way I was thinking, if I get no sensible, response is to get an Engineer to sign off on change. Any thoughts on how this might go?
Sean

I have just ordered the silent armours for the D4 and they are arriving this afternoon, so i share your concern re loading.
Speaking from a position of complete ignorance, could the different specified load ratings for each rim/tyre combination reflect different patterns of stress/strain distribution according to the different geometries of the tyres?:confused:

[AGRO]

Confusing Placard ain't it!!

[sean c]

I have been trying to get clarification on this issue from Qld Dept of Main Roads & Transport. After politely getting passed between various offices I believe I have now solved the mystery myself.
On the cover page of the Qld Transport’s guide to vehicle modifications http://www.tmr.qld.gov.au/~/media/c792a0c9-92b1-43ee-933b-7bdd8b20842f/pdf_modification_motor_vehicles2.pdf (http://www.tmr.qld.gov.au/%7E/media/c792a0c9-92b1-43ee-933b-7bdd8b20842f/pdf_modification_motor_vehicles2.pdf) it has the disclaimer below;
The contents of this publication are a guide only and cannot be used as a reference to a point of law. For a detailed explanation, refer to the Transport Operations (Road Use Management - Vehicle Standards and Safety) Regulation 1999.
I then looked up the regulation it pointed to and there is no reference to tyre placards at all!!
The only reference to tyre load is text below;
˙Wheels and tyres—size and capacity
35. The wheels and tyres fitted to an axle of a vehicle must be of sufficient size and capacity to carry the part of the vehicle’s gross mass transmitted to the ground through the axle.
The Land Rover manual also lists on page 248 the ‘Original wheel and tyre combinations’ The load index varies from 107 to 112.
I now believe Qld Transport took the easy way out in their guide book by referencing the tyre placard, which most manufactures, except for Land Rover, have the minimum load index listed.
I will follow the Qld regulations and ignore the guide book which ‘cannot be used as a reference to a point of law’, according to the disclaimer.
Don’t know what other states have but may pay to check the actual legislation rather than the guide books published by the relevant authorities.
Sean

[Graeme]

Of note is that the information required about a vehicle for Australian compliance aproval as shown on the Road Vehicle Descriptor record, does not include tyre load ratings. The tyre and rim information section only provides for tyre sizes, rim diameters and widths, offset, front and rear tracks and applicable vehicle model designations (eg S, SE, HSE).

[bbyer]

When selecting tyres, particularly for something as specialized as the D4, there are a couple of other numbers besides the Load Index or Rating, (an up to 111 number on the D4). There is also Load Range which is most often XL and Speed Rating, the V letter for the most part. My view is that the load index number, as long as it is close is not a big deal, but the Load Range is. In short, it is the difference between car tyre construction and heavier truck tyre manufacture. The speed rating is more of a heat buildup sort of thing related to load and speed.

The links below are from the Tire Rack USA site and are I think provide pretty good explanations of the three factors.

Tire Tech Information - How to Read Speed Rating, Load Index & Service Descriptions (http://www.tirerack.com/tires/tiretech/techpage.jsp'techid=35)

Tire Tech Information - Load Range/Ply Rating Identification (http://www.tirerack.com/tires/tiretech/techpage.jsp'techid=55)

Tire Tech Information - Sidewall Markings (http://www.tirerack.com/tires/tiretech/techpage.jsp'techid=33)

[mowog]

I played it safe and fitted the Conti's 255/60/18 because they had a 112 load rating which matched the requirements on the tyre placard. In the event of an incident there can be no question by the insurance company on the basis of an underrated tyre.