Tyre Load - What's the deal?

[Woody]

Chaps,

I know tyre questions have been done to death (I've read most of 'em!), so apologies.....

I need to replace a front tyre on the GS and in looking for a replacement, I'm getting a bit lost in terms of availability.

I've currently got 235/35/19 91Y P Zero Rosso's on, which are the tyres in the owners manual. In looking at getting the same tyres, there's better prices for the same tyre but with a lowe load (87).

The question is, what's the manufacturers spec? The manual doesnt have the load rating in at all. Are there implications (I'm thinking insurance wise) of going for 87 over 91?

To be fair, the difference is only £40 so not the end of the world, but if I look at other tyres, I'ld like to understand the load.

Note, I bought Falkens for the rear but have been advised by someone whos opinion I value to stick to a better brand going forwards.

Advice appreciated.

Cheers
Woody

 

[lozcb]

Chaps,

I know tyre questions have been done to death (I've read most of 'em!), so apologies.....

I need to replace a front tyre on the GS and in looking for a replacement, I'm getting a bit lost in terms of availability.

I've currently got 235/35/19 91Y P Zero Rosso's on, which are the tyres in the owners manual. In looking at getting the same tyres, there's better prices for the same tyre but with a lowe load (87).

The question is, what's the manufacturers spec? The manual doesnt have the load rating in at all. Are there implications (I'm thinking insurance wise) of going for 87 over 91?

To be fair, the difference is only £40 so not the end of the world, but if I look at other tyres, I'ld like to understand the load.

Note, I bought Falkens for the rear but have been advised by someone whos opinion I value to stick to a better brand going forwards.

Advice appreciated.

Cheers
Woody

You touched on the vital point Woody, Insurance companies are increasingly looking for any loop hole to escape claims , if you wander away from manufacturer spec , worth notifying them for clarification,


regards loz


regards loz

 

[Emtee]

A quick search seems to show the Michelins and Pirellis at 94 and 95 load rating respectively, so 670 kg's or 690 kg's.

Kerb weight of the 4200 (not sure about the 3200 or GS) comes in at 1,690 kg's, so assuming 50/50 weight distribution in both axis's, that's 423 kg's per corner.

Four adults at let's say 85 kg's average weight and 30 kg's luggage in the boot comes to 508 kg's at the front and 523 kg's at the rear.

An allowance for compressed load is necessary, and I'm guessing here but perhaps 100 kg's? per corner, so with a bit of rounding up that's 630 kg's or a load rating of 92.

At 235.40.18 the choices shown on Blackcircles come in at either 91 or 95, so I'd be going for the 95's, and there's plenty of choice across the price band.

As for the Falkens, I've been running them and rate them very highly. Even wear, grippy and not too much tram-lining given their size. I've tried both the Pirelli's and Michelins and would rate the Falkens over both of them.

 

[Woody]

Wow Miles, thats a post with a lot of thought, thanks.

OK, so it sounds like 87 is out! I belive 91 are factory fit on the GS.

As for Falkens, I've read nothing but good on them to be honest so its a tricky decision. The scarcity of new Falkens is pushing me to look at alternatives.

Loz, thanks for your reply too, much appreciated chaps.

 

[Emtee]

No Worries Woody.

So 91 on the GS. I was a little bit out on my assumptions I guess. As a matter of interest, what's the kerb weight of the GS?

I also over-sized my tyres a little to try and get a bit more wheel protection. Here are the calculations if you're interested...


Standard Rear.

265/35/18 - Overall tyre diameter of 643mm. Circumference of 2019mm. 797 revolutions per mile.

Options.

275/30/18 - Overall tyre diameter of 622mm (a difference of -21mm or -3.27% against standard). Circumference of 1955mm. 823 revolutions per mile.
275/35/18 - Overall tyre diameter of 650mm (a difference of +7mm or +1.09% against standard). Circumference of 2041mm. 788 revolutions per mile.

285/30/18 - Overall tyre diameter of 628mm (a difference of -15mm or -2.33% against standard). Circumference of 1973mm. 815 revolutions per mile.
285/35/18 - Overall tyre diameter of 657mm (a difference of +14mm or +2.18% against standard). Circumference of 2063mm. 780 revolutions per mile.


Standard Front.

235/40/18 - Overall tyre diameter of 645mm. Circumference of 2027mm. 794 revolutions per mile.

Options.

245/35/18 - Overall tyre diameter of 629mm (a difference of -16mm or -2.48% against standard). Circumference of 1975mm. 815 revolutions per mile.
245/40/18 - Overall tyre diameter of 653mm (a difference of +8mm or +1.24% against standard). Circumference of 2052mm. 784 revolutions per mile.

255/35/18 - Overall tyre diameter of 636mm (a difference of -9mm or -1.4% against standard). Circumference of 1997mm. 806 revolutions per mile.
255/40/18 - Overall tyre diameter of 661mm (a difference of +16mm or +2.48% against standard). Circumference of 2077mm. 775 revolutions per mile.


One of the calculators I used advised no more than +/-2.5% variance in diameter.

So to add a little bit more rubber to protect your rims, wider by 10mm with no change to the sidewall ratio is best whether front or back. If you want to add 20mm, then again leaving the ratio unchanged is probably the most consistent between front and back, but your speed and mileage readings will be further off.

Hope this helps.