@hq_ , @09Speed ,
Guys,
I think one key issue is not being discussed here, and I am only saying this as I am unaware of the laws in Finland for Hq_, or, Hq_, you maybe just don't care.

Therefore, I agree with what 09Speed is stating, as we are both here in the USA, and we have Federal regulations to follow, and said Federal regulation states that it is illegal to install a tire with a lower than vehicle manufacturer's standard recommendation, therefore when Bentley states that the load rating is to be "105", it is to be 105 or higher, it is not a suggestion, therefore installing a "99" or any rating lower then 105 as Hq_ stated, would be a no go, as I also believe that it is more than the tire carrying the weight sitting still, characteristics of driving and weight shifts loading onto portions of the vehicle and suspension / tires, that is where the required load standards come into play.

I will add, my GT's original tires were 275/40/19 105Y,
although my door jamb place card does not give the load rating, the manual does, and it states the standard is 105.

NOW, when I went for new tires for the B, I went with the Continental Extreme Contact Sport, I also have these on my Brabus S600 (99 / Standard Load), my Audi A8L W12 (106 / Extra Load), along with Continental Cross Contact LX Sport's on my Range Rover (108 Load), and if it wasn't for you two in this thread, I may have not realized an issue, I was going to install the Conti's in the size of 275/40/ZR20/106Y/EL (EL = Extra Load) on the Bentley, but, as the 35's on the 20 inch wheels were extremely close in overall size to the 19 inch tires, I went for the 35's, BUT, the salesman nor the installer ever said anything about the load rating changing, I now see that just by dropping from the 40's to the 35's, that dropped the load rating from 106 to 102, eventhough these 102 and 106 Conti Extreme Contact Sports are "Extra Load", it makes me wonder, is that why my front tires on the B have worn on the insides so quickly, the alignment is said to be dead on, so with the lesser load capacity and spirited driving, is that the cause, as the Audi A8L W12 does not have the front tires worn as the Bentley GT, the A8L W12 is just a nose heavy as the B, but never had an issue with the 106 rating tires on it.

Thoughts ?


A quick Google search gave this.

"AI Overview
+10Tire load ratings are not simply manufacturer's recommendations; they are mandatory safety standards regulated by law
. Operating a vehicle with tires that are not rated to carry its weight is a safety hazard and is illegal in many jurisdictions.
Legal and safety implications

• Federal regulations: In the United States, federal law mandates tire load rating standards through the National Highway Traffic Safety Administration (NHTSA). A key regulation, 49 CFR § 571.110, requires that the combined maximum load ratings of the tires on an axle must be at least as high as the Gross Axle Weight Rating (GAWR) specified on the vehicle's certification label.
• Vehicle placard: The proper tire size, inflation pressure, and load rating are specified on the vehicle's Tire and Loading Information Label, typically located on the driver's side door jamb. You must choose replacement tires that meet or exceed these ratings.

Manufacturer recommendations vs. legal limits
While you must meet or exceed the minimum load index specified by your vehicle's manufacturer, it is also important to note the difference between a tire's capacity and your vehicle's: Minimum tire requirement: When buying new tires, you can choose a load index that is higher than the manufacturer's recommendation, but never lower."

Johnny

.

 

I have seen consistent issue with under load tires and all kinds of tire wear(especially Corvettes when changing from Run-Flats and ignoring load ratings)- Alignment specs are derived with a certain load tire sidewall and when that flexs/or rolls under the tire wears differently. If you search by vehicle on Tire Rack, they eliminate certian tires that dont meet MFG specs for a reason. You should never search for tires by size. In addition a good friend totaled his Pontiac G8 and almost lost his wife on a cold 33 degree day running Pilot 4S here in Michigan. He said the rear end just let go on the expressway going 75mph on cruise-road totally dry and had been for 3 days previous-4pm afternoon. This is when myself and another friend changed tires on our CTS-V Caddy's due to wanting to drive in temps under 40 degrees, even tho neither of us drove on anything but dry roads. we both went to Pilot All Season 4 and neither had any issues since, my friend just installed his second set of Pilot All seasons last week-loves them.

 

@09Speed ,
I understand, I never searched by tire size, always by vehicle, and there are sites that state that the 275/35/ZR20 102Y fit the GT, as the 20" wheels were an option for the GT, and the tire size was the same as I purchased, the 275/35/20, and I remember searching about the 20" wheels and correct tire size back when I was ordering them, there are even posts here on 6Speed stating that the 275/35/20 were an option, and they state the 102 load rating, even Tire Rack shows the 275/35/20, but states the it is not available at this time, I even called the supplier that sold me the 275/35/20/102y tires, he claimed that the 102 is correct for the Bentley GT, as the size was an option from Bentley, not just an aftermarket tire size, and stating the the manual we all read as I posted the picture of, that it states the standard wheel/tire size, not the optional.

So, I am a little confused, as sites show the Bentley GT with the 35 tire at the 102 load rating...

Johnny

.

 

So the 275/35/20 "B" Tire fitted on my 2009 GT Speed was a 102Y, but manual just states a 275/35/ZR20 "B"-no mention of Load rating other than saying the 275/40/19 should be 105Y. I have a set of the original 275/20/ZR20 "B" marked 102Y in my Garage on the original wheels. The manual also states that Winter Tires in that size are to be 102W OR 101W. So apparently in the 275/35/20 on a Speed a 102Y is acceptable- Not sure what the heck you do on a Reg GT, but are we sure it was an option on the GT? not just std on Speed?

 

Tire rack when searching by 09 GT Speed, says they have no tires available, shows 275/40/19 as optional size which I don't know if you could get a Speed with 19" wheels. When you search a Reg GT, it also states no tires available in 275/35/20, but doesn't really show as optional size either. I don't have my Reg Gt owners book available to me , so not sure what is stated there. There is 165lbs per tire lower load rating on the 102Y vs the 105Y!? No listing in either manual for 21's, yet many have done 21s and mine has a set of 21" Vossens with 105Y, but anything 102Y and above ok? I feel fine with 105Y's on my 21's, and the 102Y was factory on 20", so good there, but if your running 19s you should have 105Y-hard to make sense of that other than lower profile less susceptible to rolling over/under? I guess I would err on the side of highest rating you can get.

 

This has to be one of the most ridiculous misconceptions I've ever heard. If you don't even know that the load rating covers full diagonal, vertical and lateral loading at maximum rated load at the limits of the traction of the tire (ie. in all conditions) - by very definition of the rating - it's quite apparent that you shouldn't even try to think.

Thank you. Again.

 

Then why does the engineer require a 2000 lb plus load rating on a tire for an axle rating of 1500 lbs? 1500 x 4 = 6000lbs which is weight of car plus the approx 800 lb people and cargo load limit, so basically the static weight of car with full tank of gas, all fluids and people/cargo. Yet the engineer says load rating on tires= 2000 x 4 = 8000lbs. Maybe your the one who shouldn't try to think? The engineer is saying the load of the tire needs to be 33% higher than the static weight of the vehicle and cargo-I'd say that is quite an additional load of tire at the vehicles limit.

Thank you!

By the way, have you check your countries laws as Johnny has noted- in US it is against the law to under load the tires on a vehicle, likely is in your country as well.

 

Where did you get your idea that an engineer has something to do with exceeding a specification determined by engineers and do you even know what GWV (gross vehicle weight) means? Listing arbitrary cargo weights suggests serious clueslessness as if your recurring denial of established facts already has for quite some time. The imaginary "under loading" (which by definition isn't the case here as I demonstrated) is another manifestation of this. The science and technology aren't debatable. Marketing and design departments can freely choose any load rating that exceeds the specified GVW for axles/tires, by 5kg or 500, and every single one of the tires and sizes that have surfaced in this "discussion" exceed that for a fully loaded FS by a sizable margin. Ergo, you've been arguing a technologically proven non-issue from the very beginning. God knows why, but even as I do have a valid clinical certification in all US states, diagnosing your "reasoning" is far beyond a charitable freebie.

You still haven't explained what possessed you to claim that 1454kg is more than 1550kg. Care to elaborate or would you like to continue evading standing behind your claims and throwing new arbitrary claims in the air time and time again, hoping in vain that one of them might stick, when they don't?

 

If you would actually do some research instead of making claims based on your "opinion" you might learn something. Bentley very clearly lists the maximum cargo capacity for each model in the owners manual, on a GT it is just under 800lbs, the GT weighs approx 5200 lbs, so the GVW is approx 6000lbs, so tires that are rated at 1500lbs are barely enough to hold the static weight of a fully loaded vehicle sitting in your garage. The engineers from Bentley have calculated that the vehicle requires over 2000lb rating on each tire to allow for the loading of a tire at the vehicle's maximum performance capabilities and Federal law requires that this tire capacity is met when replacing tires. This has been documented by both Johnny and myself. Read your owners manual and you might learn something about the tire requirements of your vehicle. Quite simple, not sure why an intelligent man like yourself is having such a hard time with this.

 

You must have missed this from Johnny's post:

A quick Google search gave this.

"AI Overview
+10Tire load ratings are not simply manufacturer's recommendations; they are mandatory safety standards regulated by law
. Operating a vehicle with tires that are not rated to carry its weight is a safety hazard and is illegal in many jurisdictions.
Legal and safety implications
Federal regulations: In the United States, federal law mandates tire load rating standards through the National Highway Traffic Safety Administration (NHTSA). A key regulation, 49 CFR § 571.110, requires that the combined maximum load ratings of the tires on an axle must be at least as high as the Gross Axle Weight Rating (GAWR) specified on the vehicle's certification label.
Vehicle placard: The proper tire size, inflation pressure, and load rating are specified on the vehicle's Tire and Loading Information Label, typically located on the driver's side door jamb. You must choose replacement tires that meet or exceed these ratings.

Also if you review Johnny's post you will clearly see the 794lb max cargo and people load on the vehicle placard that is shown just below the above statement in Johnny's post. Everything I've posted is from research, not opinion. Sorry friend, but this is pretty obvious if you do the research.

 

You don't even know that load ratings for tires are for driving, any conditions that may occur up to pushing the vehicle of the maximum weight of the rating to its very limits?

Oh my God. Don't you know anything? Or even worse, incapable of learning anything?

The load ratings are by far and wide a trivial statistic as pretty much all tires exceed the actual weight of virtually any vehicle by a huge margin. No-one this side of trucking industry hardly mentions them in any context. The only time during the ~1.5M miles and 40 years I've been driving (so far) when I've encountered load bearing ratings on a practical level is back in 1990 when I was being trained as a combat transport officer in Säkylä military base, and assigned as a rehearsal to calculate which heavy combat vehicle tires could interchangeably be used on a loaded T72 tank transport trailer (or vice versa) in emergency situations when a vehicle being deployed was out of spare parts.

Other than that, including everything from civilian heavy trucking to semi-professional motorsports, no-one generally gives a flying eff because it's largely a non issue, except you, now, as a total anomaly who hasn't even a basic understanding what load bearing rating vs. GVW means. You really think the load bearing ratings are for static weight (SIC!), as if cars aren't to be driven and ratings weren't pre-determined.

Facepalm. A massive one.

 

You've spent too much time in a sauna and baked your brain-apparently in your country common sense is not in use!
It's against Federal Law to install tires lower than the load rating required by the manufacturer of vehicle, and for good reason. I'm done talking to you, go find a snow bank to sit on or whatever you do. Go drive your performance tires not rated for cold during freezing weather and install under rated tires on your car, I don't care as long as the other members here know that is not the correct way to do things. You can do whatever you want, lol, such a joke. In the US, they made it a law so unscrupulous tire dealers did not sell their customer underrated tires that would be unsafe just to be the lowest price. This is why Tire Rack and other Large Tire dealers will not list any underrated tires for a Bentley or any other car because they would then be liable for breaking the law and any damage or injury caused. Really not that hard to understand, for most people with common sense they could figure it out, just not you.

 

Does your claim that you've been involved with tires for 50 years mean that you've been sniffing hydrocarbon fumes out of them? You're the only one who has even mentioned a load rating lower than GWV here. Or have you snorted that insightful piece of information out of a tube of glue or what? This is getting ridiculous, you write a lot but seem to be severely lacking in reading comprehension. Including but not limited to basic facts concerning load ratings and weights. I thought there might be something wrong with you when you didn't even have a clue about the differences between Speed and base model engines and started dancing in circles when that common knowledge was brought to your attention, but there was no indication that your profound ignorance extended to other fields or was this serious.

But, amuse us, please let us have your explanation how 1545kg exceeds 1550kg as you claimed, without adding imaginary passengers and luggage which by definition are included in GVW. You've been asked this three times now after you implied this and the best you can come up with is a projection of your own situation you've made an exhibition of time and time again now, which can only be politely described as being paralyzed from the neck up. A smaller weight exceeding a larger one is truly a gem of yours, a prime example of what Scott Adams called induhvidualism. Care to elaborate or still running away like so many times before?

 

Maybe you should read again because I never mention GVW in any post on this Thread-ever! GVW is the curb weight of the vehicle and the max cargo and occupant weight as specified by the manufacturer - roughly Bentley GT curb weight 5200lbs, Max cargo and occupant weight specified by Bentley as Johnny has documented in this thread is 794lbs(it's listed on a photo I've attached a link to of vehicle tire load placard affixed to car)-so approx 6000lbs which is max static weight of vehicle and contents or GVW (Gross Vehicle Weight) so 1500lb load rated tires do not leave any capacity for the additional load a tire might see at top speed and under max cornering or braking, thus inadequate. I know it's awfully complicated #1 and #2 it's against the law to put a tire that is under 1874ld load rating 102 for 275/35/20 or 2039lb load rating 105 for 275/40/19. I do not know why the 20's are less than 19's, but I suspect it has something to do with reduced sidewall to flex, but the why is irrelevant because the law is the law. This is not a race track where you can do as you wish, and yes some insurers will refuse coverage if you are in an accident with under rated tires. Is this clear enough for you

Here is your statement:
"
As far as the load bearing capacity is concerned, 99 officially suffices for the curb weight of a Bentley. Not necessary an ideal choice but as an example of how far from OEM you can go and still be fully road legal and insured. And if you're driving like a geriatric or people who buy Bentleys for show and don't have a clue what trail braking into a fast corner - for example - means, it'll work perfectly in practise too."

You state here fully road legal and insured-which is not true as it is against the law to install a tire that does not meet or exceed the manufacturer's specified load rating. So here you go Mr. Genius, your wrong!

Link for tire and loading placard:

https://cimg6.ibsrv.net/gimg/www.6sp...7948af9a79.jpg

 

This is where you've misunderstood and wrong. The load rating is specified in fully loaded static the gross vehicle/axle weight of the vehicle and once matched or exceeded, includes all driving conditions including weight transfer ie. acceleration, braking and cornering with the vehicle. Not just having it sit as a static object, which would be insane and totally useless. These are reference figures for each other. A tire with a (static) load rating that exceeds the (static) gross vehicle weight for a given axle is perfectly legal and once matched or exceeded, capable of supporting dynamic loads in all driving conditions by definition.

If your interpretation had any merit, you couldn't drive the car at all because even hitting a dip or bump resulting in far higher dynamic loads can easily exceed the tire load rating by up to several orders of magnitude.

I'm not sure where you came up with this elaborate conspiracy theory you're now repeating ad nauseum as the reality is as simple as comparing two figures, weight and load rating, and being done with it. Check anywhere, ask anyone, read any literature about the subject; this is exactly how it is, with no room for speculation.

Let's have Google Gemini simplify the reality for you:

How to find and use the load index:

• Locate the number on the tire's sidewall:
  The load index is a two or three-digit number found within the tire's service description, typically between the tire's dimensions and the speed rating.
• Consult a load index chart:
  Use a standardized chart, such as those provided by Pirelli or Les Schwab, to find the maximum carrying capacity in pounds or kilograms corresponding to your tire's load index number.
• Determine your vehicle's total capacity:
  Multiply the load capacity of a single tire by the number of tires on your vehicle to find the total weight your tires can carry.
• Ensure compatibility with your vehicle:
  Verify that the load index of your tires meets or exceeds the load capacity specified by your vehicle manufacturer, which can be found on the vehicle's door jamb label or in the owner's manual