A question on tyre ratings

[oobster]

Fellow PH'ers.

I have a query on tyre ratings.

Current car is fitted with 225/40 18 91Y tyres (fitted by manufacturer when the car was new). Car is a 2010 Octavia VRS.

I have ordered some 19's, and have asked the company supplying me with the wheels to fit 225/35 19 tyres before they courier them up to me. Can't fit 235's as they would rub (so I am told).

The tyre I have decided to go with is the Vredestein Ultrac Sessantas, which according to the Vredestein website are rated at 88Y but also have 'XL' next to the rating which I am fairly confident is Xtra Load.

Am I ok going for 88Y XL rating when the car is currently fitted with 91Y-rated tyres?

Ta.

[v8will]

Providing the front axle allowable weight is less than 1120KG then yes, it would be OK.

[weezb]

oobster said:

Fellow PH'ers.

I have a query on tyre ratings.

Current car is fitted with 225/40 18 91Y tyres (fitted by manufacturer when the car was new). Car is a 2010 Octavia VRS.

I have ordered some 19's, and have asked the company supplying me with the wheels to fit 225/35 19 tyres before they courier them up to me. Can't fit 235's as they would rub (so I am told).

The tyre I have decided to go with is the Vredestein Ultrac Sessantas, which according to the Vredestein website are rated at 88Y but also have 'XL' next to the rating which I am fairly confident is Xtra Load.

Am I ok going for 88Y XL rating when the car is currently fitted with 91Y-rated tyres?

Ta.

Hmmm, I'd inform your insurance company. You would have to be very unlucky to be in an accident and have the tyres spotted as being different to the manufacturers but this is just the kind of thing they'd use to try and weasel out of a payout.

[Deva Link]

weezb said:

Hmmm, I'd inform your insurance company.

The insurance company needs to be told about the wheel change anyway. I would just try and gloss over the load index issue - that's a massive can of worms.

[oobster]

My insurance company (eSure, who have been very good with other mods on the car) will definitely be told about the wheel change, just unsure about the speed and load ratings. The speed rating will stay the same (Y) but the load rating will go down, but then the Sessants are 'Extra Load' so does this mean they'll be the same (or 'better') than 91?

[joebongo]

If the wheels/tyres are within spec for the manufacturer (ie: could have been optioned at new) then I thought there was no need to inform them.

I assumed the speed rating was also a red herring unless you chose a rating which was less than the speed you drive at (ie: a sub-70mph rating in the UK).

I also assumed XL was a heavier load rating.

I am ready to be corrected on the above points!

[weezb]

joebongo said:

If the wheels/tyres are within spec for the manufacturer (ie: could have been optioned at new) then I thought there was no need to inform them.

I assumed the speed rating was also a red herring unless you chose a rating which was less than the speed you drive at (ie: a sub-70mph rating in the UK).

I also assumed XL was a heavier load rating.

I am ready to be corrected on the above points!

There was some difference of opinion over on the Briskoda forum over the correct tyres for the Fabia vRS Mk1. Someone had German documentation that indicated 205/45/R16 83V was acceptable, others swore 83W was the correct tyre. So, I contacted Skoda UK who informed me 205/45/R16 83W was the correct tyre and anything else would have insurance implications.

[Deva Link]

joebongo said:

I also assumed XL was a heavier load rating.

I'm not totally sure on this, but I don't think it increases the rating beyond the stated code number. XL tyres are reinforced and are often standard with very low profiles.

I think it would be dodgy from an insurance point of view to go below the load index of tyre that the car was built with. Problem if you do that is it breaks the vehicle's type approval.

[mmm-five]

An XL tyre is designed to only achieve it's certified load rating when it's pressurised at a higher level (usually above 2.5 bar) than a standard load tyre (2.0-2.5 bar).

So if you put the the Skoda's recommended bar in (2.5 bar for example), then the 88XL won't be pressurised enough to conform to its designed higher load rating.

And before you just go away and put more air in to raise the load limit you may want to check what your owner's manual says about load ratings - as just pumping up a tyre on a car that doesn't need that extra pressure may negatively affect handling, braking and tyre wear.

The crucial point - and the one the insurance company / MOT / police would most probably look at - would be what minimum load rating the manufacturer lists, and if you go below this (whether standard or XL) then you may be on sticky ground in the event of an accident or MOT check.

[oobster]

The Vredestein website has a 'tyre language' pop-up, which says "The load-index figure denotes the maximum load capacity of a tyre when driven at maximum speed". LI 88 = 560KG, LI 91 = 615KG.

There is a sticker at the bottom of the passenger-side B-pillar with the following information on it:

1940Kg
3340Kg
1- 1100kg
2- 1100kg
650Kg

It doesn't, however, list what these figures relate to but I suspect it is axle weight, kerb weight etc.

Must admit, I am no clearer now than I was when I started this thread. Having already had over £1600 debited out of my bank account for these wheels/tyres I am now worried!

Does anyone know of a 225/35 19 tyre that is rated to 91Y?

[Caulkhead]

Whatever you do it will probably not drive as well on the 19's as it did before, however two questions:

1) What tyre pressures are recommended for the old tyre/wheel combo and what do you intend to inflate the 19's to?

2) Will 225/40/19 fit without rubbing? If so they are commonly available with more suitable LI ratings for your car.

[busta]

oobster said:

1: 1940Kg
2: 3340Kg
3: 1- 1100kg
4: 2- 1100kg
5: 650Kg

At a guess:

1: Gross vehicle weight.
2: Gross train weight (vehicle + trailer)
3: Maximum axle weight
4: Maximum axle weight (doesn't matter which axle is which seeing as they are the same!)
5: Not sure, could be maximum load in car?

[oobster]

v8will said:

Providing the front axle allowable weight is less than 1120KG then yes, it would be OK.

So, on the Vredestein website it says maximum load capacity for LI88 is 560KG, so I assume this is where your 1120KG comes from (560 x 2)?

If this is correct, then the sticker on my B-pillar seems to suggest the maximum axle weight is 1100KG, so if is the case and that is UNDER the 1120KG, I should be ok putting LI 88 tyres on?

[Deva Link]

My *guess* would be that, from a technical point of view, it's not super critical.

I would say your biggest problem is going to be getting it past the insurance company if they ask for details. Having said that, I bet there's loads of people using the wrong load rating tyres, especially not using XL tyres where they were originally specified.

[busta]

oobster said:

So, on the Vredestein website it says maximum load capacity for LI88 is 560KG, so I assume this is where your 1120KG comes from (560 x 2)?

If this is correct, then the sticker on my B-pillar seems to suggest the maximum axle weight is 1100KG, so if is the case and that is UNDER the 1120KG, I should be ok putting LI 88 tyres on?

Yes, you'll be fine.

[Lostprophet]

My car is fitted incorrectly with 225/35R19 88Y. The Audi S5 should have 255/35R19 97Y.

I have raised the issue with the dealer I have bought the car from as they fitted the wrong size. I actually paid them as a part extra for the tyre fit so I am not particularly pleased with the issue. Insurance will be invalidated on the event of a claim and also wrong load index tyres can blow. Considering my car is already heavy and when travel on day trips its fully loaded tyre blows are not a risk I want to take!

[Frances The Mute]

busta said:

oobster said:

So, on the Vredestein website it says maximum load capacity for LI88 is 560KG, so I assume this is where your 1120KG comes from (560 x 2)?

If this is correct, then the sticker on my B-pillar seems to suggest the maximum axle weight is 1100KG, so if is the case and that is UNDER the 1120KG, I should be ok putting LI 88 tyres on?

Yes, you'll be fine.

The load rating is not just about the weight of the vehicle of the load carried. The tyre has to be able to withstand the forces that the vehicle generates in terms of acceleration, braking, lateral stability etc.

You need to maintain or improve upon the service description of the OE tyres.

[R0G]

busta said:

oobster said:

1: 1940Kg
2: 3340Kg
3: 1- 1100kg
4: 2- 1100kg
5: 650Kg

At a guess:

1: Gross vehicle weight.
2: Gross train weight (vehicle + trailer)
3: Maximum axle weight
4: Maximum axle weight (doesn't matter which axle is which seeing as they are the same!)
5: Not sure, could be maximum load in car?

I wonder if the 650 kgs is for an unbraked trailer ..... if the kerbweight is about 1300 then that would be correct because the law states that an unbraked trailer cannot be more than half the kerbweight