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[mcd840]

Do any of you who have dti vecs or omegas bother with extra load tyres on the front ? Just asking as the sidewalls on my fronts seem very bulgy even at correct psi. Or does it not make much odds

Cheers

[Entwood]

I have extra load all round  (3.2 elite saloon) but I do a LOT of towing and the 'van is 1600kgs .. so I don't take risks ..

[05omegav6]

XL all round here...

And given the gross weight of an Omega is around 2300kg or 575kgs per corner...

You would be well advised to fit XLs all four of your tyres, as non XLs might not carry the weight, and might cause an issue if you prang it and tyres are found to contribute

[D]

The Omega was built around standard tyres if I am not mistaken. So why would the XL tyres be of any consequence in a prang? Would it not be the other way round as XL were not the standard tyres that came with any Omega?

[05omegav6]

To be clear...

http://www.blackcircles.com/general/load-rating

 

[mcd840]

They all come up as 91 v for me...

[biggriffin]

A tyre based thread........nooooo

[Marks DTM Calib]

The important thing is that the load rating matches or exceeds that which the manufacturer specifies. 

Towing etc. should not result in the manufacturers spec being exceeded (for example, the max nose weight on the tow bar is circa 75Kg which is bugger all extra assuming the pikey wagon/trailer brakes are working correctly.) 

[tunnie]

The important thing is that the load rating matches or exceeds that which the manufacturer specifies. 

Towing etc. should not result in the manufacturers spec being exceeded (for example, the max nose weight on the tow bar is circa 75Kg which is bugger all extra assuming the pikey wagon/trailer brakes are working correctly.) 

I make that around ~12 stone?

So having two people in the back, would be more than weight of a burger van?

[chrisgixer]

Do any of you who have dti vecs or omegas bother with extra load tyres on the front ? Just asking as the sidewalls on my fronts seem very bulgy even at correct psi. Or does it not make much odds

Cheers

XL has little to do with that ime. What tyres are they? And do you have any handling issues with the car, possibly as a result? Ime I've had better handling results with stiffer side wall tyres. Don't get that water balloon on each corner sensation anyway.

[Kevin Wood]

Tyres have always had a load rating. "XL" is just a recent marketing gimmick designed to attach some sort of extra value to tyres with a high LR. As said, match the load rating to the manufacturer's spec and, regardless of whether the tyre is marketed as an XL, all will be fine.

[05omegav6]

Without realising the implications, if someone fitted 88 rated tyres to their Omega estate on cost grounds, then they would be quite close to the tyres limit, and if they suddenly found themselves in a highload situation, such as emergency braking, then suddenly the front tyre loads might increase by 50% due to weight transfer. Even the gentlest of drivers could overload an underated tyre in such circumstances 

Gimmick or no, the XL rating does at least imply a higher load rating for any given tyre size

[Entwood]

The important thing is that the load rating matches or exceeds that which the manufacturer specifies. 

Towing etc. should not result in the manufacturers spec being exceeded (for example, the max nose weight on the tow bar is circa 75Kg which is bugger all extra assuming the pikey wagon/trailer brakes are working correctly.) 

Totally agree ... but there are a few additions .... many folks will have 2 adults + 2 kids in the car + a boot full of stuff when towing .. so the tow bar load is additional to the "normal" weight, and has a degree of "leverage" given the position of the towbar.

In my case .. and the "worst case" scenario ... off to France so the roof box will be on and full , around 60 kgs, 2 bikes - another 20 kilos, LPG tank full - 40 kilos and then all the other crap we take .. BBQ, coldbox, awning, poles etc etc etc on the back seat as I prefer to have a heavy(ier) car and light(er) van when towing.

All this plus driving for 4-5 hours in (hopefully) warm conditions will put extra stress on the tyres, so I choose to use XL purely as a precaution ...

[taitinson]

Towing etc. should not result in the manufacturers spec being exceeded (for example, the max nose weight on the tow bar is circa 75Kg which is bugger all extra assuming the pikey wagon/trailer brakes are working correctly.) 
[/quote]

Maybe the ton and a half of rubble in my trailer which had the axle positioned towards the rear end of it is linked to the towbar having bent on my estate........

[Marks DTM Calib]

The important thing is that the load rating matches or exceeds that which the manufacturer specifies. 

Towing etc. should not result in the manufacturers spec being exceeded (for example, the max nose weight on the tow bar is circa 75Kg which is bugger all extra assuming the pikey wagon/trailer brakes are working correctly.) 

Totally agree ... but there are a few additions .... many folks will have 2 adults + 2 kids in the car + a boot full of stuff when towing .. so the tow bar load is additional to the "normal" weight, and has a degree of "leverage" given the position of the towbar.

In my case .. and the "worst case" scenario ... off to France so the roof box will be on and full , around 60 kgs, 2 bikes - another 20 kilos, LPG tank full - 40 kilos and then all the other crap we take .. BBQ, coldbox, awning, poles etc etc etc on the back seat as I prefer to have a heavy(ier) car and light(er) van when towing.

All this plus driving for 4-5 hours in (hopefully) warm conditions will put extra stress on the tyres, so I choose to use XL purely as a precaution ...

Yes but as said, the load ratings for the tyres are based on the manufacturers max load calculations (e.g. fully laden) which will have already considered those factors including the nose weight 

[Yasmine Lee]

the vin plate on your car will tell you the max front/rear axle weight. half these and you will know what the manufacturer indents on each corner. make sure your tyres match or exceeds these weights.

simples

[TheBoy]

The specs in the manual suggest 93 IIRC. Thus anything 93 or higher would comply with insurance.

[mcd840]

Do any of you who have dti vecs or omegas bother with extra load tyres on the front ? Just asking as the sidewalls on my fronts seem very bulgy even at correct psi. Or does it not make much odds

Cheers

XL has little to do with that ime. What tyres are they? And do you have any handling issues with the car, possibly as a result? Ime I've had better handling results with stiffer side wall tyres. Don't get that water balloon on each corner sensation anyway.

The tyres are barun bravuris 2's. Handling etc all fine and wear very well for being on the front of a diesel ! As said the sidewallz are like water balloons. Thats my only complaint...

[05omegav6]

If they're mishaped, then either the pressures are wrong, the tyres are too low a rating/wrong size or both

Double check the Vectra manual for the wheel size fitted. Do not go by what is already fitted to the car, as that could well be wrong

[D]

The specs in the manual suggest 93 IIRC. Thus anything 93 or higher would comply with insurance.

I agree. 94 is what is currently sold as standard tyres for the omega and 97 as XL. I have not seen an 88 rated tyre in an Omega size ever. I am not sure where Al is getting that info from?

I still think the 97/XL is a marketing gimmick and often there is a cost implication to the higher load rating. Which people are happy to pay for due to a perceived safety benefit.

On the other hand if the XL costs the same as standard rated tyres, then go for it.

[05omegav6]

I plucked 88 as an example

The higher the load rating, the stronger the tyres construction, ergo, the better it withstands the rigours of day to day abuse/pot holes/speed humps overloading etc...

91 are rated to 615kg, 93 to 650kg and 98 to 750kg... I know which I would rather have on my 2 ton car

[05omegav6]

The Max permissible weight of my estate is approximately 2300kgs iirc, split 1100 kgs on the front axle and 1200 on the rear.

If I fit 93 rated tyres, that allows for a total of 1300kgs per axle... under heavy braking, the centre of gravity will move forward. How far forward do yo think it needs to move to overload the front tyres?

Ok you might say that this is an extreme example, but overload them, even for a moment, repeatedly and you'll run the risk of fatiguing the tyres, possibly to the point of failure.

[TheBoy]

I would say that the best handling tyres I've tried were 94...   ...not always convinced that harder sidewall is always better.

[05omegav6]

I would say that the best handling tyres I've tried were 94...   ...not always convinced that harder sidewall is always better.

And straight back into subjectivity without reference

Softer sidewalls might offset the harshness of larger diameters, but tyre width and pressure all play a part in tyre feel...

[TheBoy]

I would say that the best handling tyres I've tried were 94...   ...not always convinced that harder sidewall is always better.

And straight back into subjectivity without reference

Softer sidewalls might offset the harshness of larger diameters, but tyre width and pressure all play a part in tyre feel...

Aye, subjective.

The best tyres from a grip and straight line stability point of view have been 94 (and Dunlop ).  The worse were 97 (and Continental).  The GY F1's I'm running are 97, and they are bad enough, even Mrs TB complains about them .

[TheBoy]

But that's not scientific, more coincidental I think. But load rating will affect handling I suspect...   ...and not always for the better (or worse)

[Vamps]

My Honda is 98..........

[chrisgixer]

Do any of you who have dti vecs or omegas bother with extra load tyres on the front ? Just asking as the sidewalls on my fronts seem very bulgy even at correct psi. Or does it not make much odds

Cheers

XL has little to do with that ime. What tyres are they? And do you have any handling issues with the car, possibly as a result? Ime I've had better handling results with stiffer side wall tyres. Don't get that water balloon on each corner sensation anyway.

The tyres are barun bravuris 2's. Handling etc all fine and wear very well for being on the front of a diesel ! As said the sidewallz are like water balloons. Thats my only complaint...

Nothing to worry about then.

Smaller wheels give higher side walls, and some tyres look a bit balloon like as a result. It's not a structural defect.

Maybe lower profile tyres on bigger wheels would help aesthetically.

[chrisgixer]

But that's not scientific, more coincidental I think. But load rating will affect handling I suspect...   ...and not always for the better (or worse)

I see where the "tyres are subjective" argument comes from now. Its only subjective if discussed in a subjective manor, as here. A factual approach is needed here I think.

Lazy bloody admin. Facts please

[D]

The Max permissible weight of my estate is approximately 2300kgs iirc, split 1100 kgs on the front axle and 1200 on the rear.

If I fit 93 rated tyres, that allows for a total of 1300kgs per axle... under heavy braking, the centre of gravity will move forward. How far forward do yo think it needs to move to overload the front tyres?

Ok you might say that this is an extreme example, but overload them, even for a moment, repeatedly and you'll run the risk of fatiguing the tyres, possibly to the point of failure.

Thats just conjecture isn't it? Is there any real evidence rather than a theory that they could overload/fatigue? I havent heard of Omegas suffering excessive blow outs so far. And that would be the case if your theory was true as they were originally issued with 93/94 rated tyres.

To counter your argument, TB allegedly drives like a teenager on 94 rated tyres and he hasn't suffered excessive blowouts/fatigue has he?

I am no physicist, but the weight limit you refer to would be the compressive force from braking. I would think the tensile force on the tyre would have more bearing on failure/blowouts rather than the compressive force. After all braking involves lots of friction and tensile forces on the tyre rather than sheer compression.

Perhaps our resident engineer could enlighten us?

[05omegav6]

Braking is one obvious example of when an axle, and therefore the tyres, might become momentarily overloaded, but cornering is the other scenario... a sweeping bend is another and the higher the speed, the greater the weight transfer, and therefore the greater the load on the outer tyres.

Yes the numbers might be conjecture, but braking a fully laden car mid corner due to external factors could see a third of the cars weight (or more) over acting on the outside front wheel. So using my example, that's around 760kgs, so potentially overloading a 94 rated tyre by 100+kgs.

Generally speaking the tread will probably wear out before the sidewall, but even the most careful driver will encounter potholes, kerbs, bumps on and off driveways, and speed humps, all of which have the potential to weaken the structure of the tyre.

[Marks DTM Calib]

The Max permissible weight of my estate is approximately 2300kgs iirc, split 1100 kgs on the front axle and 1200 on the rear.

If I fit 93 rated tyres, that allows for a total of 1300kgs per axle... under heavy braking, the centre of gravity will move forward. How far forward do yo think it needs to move to overload the front tyres?

Ok you might say that this is an extreme example, but overload them, even for a moment, repeatedly and you'll run the risk of fatiguing the tyres, possibly to the point of failure.

Which actually is a nothing test sadly Al as going on that basis, even the max rated tyre will be overloaded and hence they are rated to much higher peak side wall loadings.

The tyre wall will not explode or fatigue under short term excess load, its all about continual flex of the tyre wall due to excess load which will result in a side wall blow out, similar to an under inflated tyre. 

[05omegav6]

As demonstrated by the relatively low failure rate of car tyres...

Trouble with tyres is that there are so many variables which affect their behaviour and performance...

Failure of the sidewall is more likely at lower pressures, not only as as that generates heat which softens the rubber, (great for grip, and perceived performance Tb/Chris), but it allows greater flexing of the sidewall, which could accelerate the fatigue effect on the reinforcement. A combination that lends itself to sidewall failure...

[TheBoy]

But that's not scientific, more coincidental I think. But load rating will affect handling I suspect...   ...and not always for the better (or worse)

I see where the "tyres are subjective" argument comes from now. Its only subjective if discussed in a subjective manor, as here. A factual approach is needed here I think.

Lazy bloody admin. Facts please

Ahhh, but we know the facts. Fit Dunlop Sport Maxx TT, and all your grip and stability problems go away .  Shame they aren't made any more 

[TheBoy]

As demonstrated by the relatively low failure rate of car tyres...

Trouble with tyres is that there are so many variables which affect their behaviour and performance...

Failure of the sidewall is more likely at lower pressures, not only as as that generates heat which softens the rubber, (great for grip, and perceived performance Tb/Chris), but it allows greater flexing of the sidewall, which could accelerate the fatigue effect on the reinforcement. A combination that lends itself to sidewall failure...

Aside from Mrs TB driving too far on a tyre rapidly losing air, I've never had sidewall damage on any Omega.  I've always managed to "get my money's worth" from the tread first.

I'm sure GM specced it to leave enough headroom, even 4 up with luggage.

[chrisgixer]

As demonstrated by the relatively low failure rate of car tyres...

Trouble with tyres is that there are so many variables which affect their behaviour and performance...

Failure of the sidewall is more likely at lower pressures, not only as as that generates heat which softens the rubber, (great for grip, and perceived performance Tb/Chris), but it allows greater flexing of the sidewall, which could accelerate the fatigue effect on the reinforcement. A combination that lends itself to sidewall failure...

Aside from Mrs TB driving too far on a tyre rapidly losing air, I've never had sidewall damage on any Omega.  I've always managed to "get my money's worth" from the tread first.

I'm sure GM specced it to leave enough headroom, even 4 up with luggage.

Given the attention they paid to the set up figures, I wouldn't bet on that. Al all, personally.

[TheBoy]

As demonstrated by the relatively low failure rate of car tyres...

Trouble with tyres is that there are so many variables which affect their behaviour and performance...

Failure of the sidewall is more likely at lower pressures, not only as as that generates heat which softens the rubber, (great for grip, and perceived performance Tb/Chris), but it allows greater flexing of the sidewall, which could accelerate the fatigue effect on the reinforcement. A combination that lends itself to sidewall failure...

Aside from Mrs TB driving too far on a tyre rapidly losing air, I've never had sidewall damage on any Omega.  I've always managed to "get my money's worth" from the tread first.

I'm sure GM specced it to leave enough headroom, even 4 up with luggage.

Given the attention they paid to the set up figures, I wouldn't bet on that. Al all, personally.

The designers and bolt-em-together peeps have different agendas 

[Auto Addict]

The important thing is that the load rating matches or exceeds that which the manufacturer specifies. 

Towing etc. should not result in the manufacturers spec being exceeded (for example, the max nose weight on the tow bar is circa 75Kg which is bugger all extra assuming the pikey wagon/trailer brakes are working correctly.) 

Totally agree ... but there are a few additions .... many folks will have 2 adults + 2 kids in the car + a boot full of stuff when towing .. so the tow bar load is additional to the "normal" weight, and has a degree of "leverage" given the position of the towbar.

In my case .. and the "worst case" scenario ... off to France so the roof box will be on and full , around 60 kgs, 2 bikes - another 20 kilos, LPG tank full - 40 kilos and then all the other crap we take .. BBQ, coldbox, awning, poles etc etc etc on the back seat as I prefer to have a heavy(ier) car and light(er) van when towing.

All this plus driving for 4-5 hours in (hopefully) warm conditions will put extra stress on the tyres, so I choose to use XL purely as a precaution ...

Yes but as said, the load ratings for the tyres are based on the manufacturers max load calculations (e.g. fully laden) which will have already considered those factors including the nose weight 

Interesting, Blackcircles recommend XL on mine, but the tyres fitted (original factory) are not XL - confused.com

....but the handbook gives tyre pressures for both....

[chrisgixer]

As demonstrated by the relatively low failure rate of car tyres...

Trouble with tyres is that there are so many variables which affect their behaviour and performance...

Failure of the sidewall is more likely at lower pressures, not only as as that generates heat which softens the rubber, (great for grip, and perceived performance Tb/Chris), but it allows greater flexing of the sidewall, which could accelerate the fatigue effect on the reinforcement. A combination that lends itself to sidewall failure...

Aside from Mrs TB driving too far on a tyre rapidly losing air, I've never had sidewall damage on any Omega.  I've always managed to "get my money's worth" from the tread first.

I'm sure GM specced it to leave enough headroom, even 4 up with luggage.

Given the attention they paid to the set up figures, I wouldn't bet on that. Al all, personally.

The designers and bolt-em-together peeps have different agendas 

The designers think up to 2.45 camber is in tolerance, iirc. What's that to do with assembley ?