Tyres

[Oversize]

I have just found another VERY GOOD reason for not increasing the tyre width beyond 225mm:
You can't store the spare tyre in the boot wheel well, and lower the boot floor lid onto the spare tyre, so that the lid sits flush with the boot floor, if the tyre width exceeds 225mm.

I would find that annoying.

It also implies that you can't go less than a 60% profile, unless you leave the tyre outside diameter too small. Another impliction is of benefit to the suspension: the bushes in the suspension don't receive an overly harsh time, with low profile tyres.

Why even carry a spare?? In Victoria you don't need one to be legal unless you're a taxi who needs a full size spare. Get roadside assist, keep the car light and save fuel.

If you do insist on a spare go for one that fits in the boot and treat it as a space saver. 80kmh max when fitted unless all your other tyres are the same. That's what I'll be doing since my rear tyres will be wider than my fronts and I can't choose which tyre might go flat....

 

[SEL_69L]

Thankyou for the more detailed information regarding weights than I guesstimated.

It is possible to know the exact safety margin for 96 load rated tyres fitted to the front of a 6.9, with the info. you have provided. It is also worthwhile to know that the correct load rated tyre for the front of a 6.9 is 97.

15" wheels from a W126 are perfectly OK to use on a 6.9, because the width and offset are exactly the same. If you have the same wheel offset as for 14" Bundts, the geometry for zero offset steering is maintained. The fitting of 15" wheels opens up the range of good quality tyres that may be commonly available. This also means cheaper tyre prices.

Original equipment tyres for the later model Toyota Taragos are nearly identical to the tyre requirements of a 6.9, with W126 15 slot wheels.
Toyota Tarago: 215/15/65 96H
6.9: 215/15/65 97H


With zero offset steering, the axis of the kingpin passes through the middle of the contact patch of the tyre on the road. If that is not maintained, the steering becomes heavier, and tyre wear under cornering conditions is biased to one side of the tyre. It is easy to identify a vehicle equipped with zero offset steering. The front wheels LOOK to be way off vertical when the steering wheel is on hard left or right lock. Almost all current production cars have some element of zero offset design approach in the steering geometry.

 

[Oversize]

The safety margin on the front is the difference between the maximum GVM on each wheel and the minimum load rating on each tyre in kg. Same with the back. So that means:

Front

97 (730kg) - (1245kg/2) = 107.5kg each side

Rear

97 (730kg) - (1175kg/2) = 142.5kg each side

So basically MB provided tyres on the front that can carry 107kg more than the capacity of the vehicle on each side and 142kg on the rear.

Doing the same with 96 rated tyres your get 20kg less:

Front: 87.5kg

Rear: 122.5kg

Just remember that's the SAFETY MARGIN, not the payload you can carry above the kerb weight

 

[Oversize]

With zero offset steering, the axis of the kingpin passes through the middle of the contact patch of the tyre on the road. If that is not maintained, the steering becomes heavier, and tyre wear under cornering conditions is biased to one side of the tyre. It is easy to identify a vehicle equipped with zero offset steering. The front wheels LOOK to be way off vertical when the steering wheel is on hard left or right lock. Almost all current production cars have some element of zero offset design approach in the steering geometry.

That would suggest you can't use anything other than et30 on a W116. However AMG offered wheels with et11 and personally I'll trust their judgement. More than that and I believe it's likely you'll strike problems. Most modern MB wheels have very high offsets (above et30) and they cannot be fitted without spacers as they rub on the inner guards. In Victoria spacers are illegal unless they're original equipment

 

[Oversize]

Even though the payload has been determined to be 485kg, that doesn't mean you could put all that in the boot, because the maximum GVM isn't evenly distributed front to rear. If you convert to percentages it's a little clearer:

2420kg total (100%)
1245kg front (51%)
1175kg rear (49%)

So if you distribute the payload in the same way you get a payload of:

Front: 247kg
Rear: 238kg

Bearing in mind it'd be rather difficult to add 247kg over the front axle since there's no-where to store anything, it leaves you adding no more than 238kg into the boot. Or 2 x 75kg mates in the back seat and 88kg in the boot. Or 3 x 75kg mates in the back seat and 13kg in the boot!

All very mathematical and it sounds very interesting, but in practice if you add 10kg to the boot, some of it will be carried by the front wheels. It all depends where the weight's positioned in relation to the rear axle. That fact adds so many variables that the only way to know for sure is to run the car over a weighbridge, one axle at a time. I'd love to try it one day....

 

[Styria]

What fascinating discussion and facts being propagated. Some of it probably goes over my head to some degree, but I nevertheless would like to give credit where due - and, in this instance all very much deserved.

To get back to simplicity, there is a question I would like to pose: Some little while ago, one of our esteemed TK members had some 215.70.14 Maxxis fitted, with the appropriate (?) white wall band on the outside - I would respectfully suggest a definite improvement in appearance (!). However, what method or material would be useful in cleaning the white band ? Any suggestions would be welcome. BTW, those Maxxis seem to work and perform well, and they're not too bad in the "Looks" department. Regards. Styria

 

[BenzBoy]

I use White Magic - http://www.whitemagic.biz/
Cut off a small strip and using the same carwash as for the rest of the car, simply wipe around the whitewalls a few times. After you have done it a few times the whitewalls will be whiter than if you used solvent.
It's dead cheap and dead simple.
Regards,
Brian

 

[Michel]

There is a question I would like to pose: Some little while ago, one of our esteemed TK members had some 215.70.14 Maxxis fitted, with the appropriate (?) white wall band on the outside - I would respectfully suggest a definite improvement in appearance (!). However, what method or material would be useful in cleaning the white band ? Any suggestions would be welcome. BTW, those Maxxis seem to work and perform well, and they're not too bad in the "Looks" department. Regards. Styria

I was unaware that Maxxis tyres were available with a white band!

Nevertheless, The best way I found to clean the whitewalls of my late Queen of Sheba was plain old thinners...
No scrubbing and no hard yakka.
Just pour some on a rag and wipe seriously et voila!!
I used to clean four tyres in less than 15min.