tyres for 996 c4

[johnnys]

I drive back roads In New Zealand very hard. I drive a 996 C4 2002 The roads here are very rough.

I found I get 7,000km from a pirelli pzero rear tyre and 15,000km from a front tyre. alternatively I use michelin pilot sports. I get 18,000 km from a rear tyre and 25k km from a front.

I find if I run the pilot sports front and rear the PSM cuts in a odd times on the front wheels as the tyres dont have the same grip as that of the pirelli's. This happens at high speeds on uneven roads and can be very unnerving. it only happens with the pilot sports and not the pzeros(on the front)

So what I did and would like feed back on is I am running the PZero's (pirelli) up front and the Pilot sports on the rear(michelin). This means they wear at the same rate. I also get the front end grip I need and can also accerate hard without nearly hearing the rubber wear off the rear tyres (as when I run pirelli on the rear after every drive I measure the tread and for a good run I lose nearly 2 mm)as the michelin at the back are harder.

Now all the manuals I read and car mags when they do tyre reveiws say to always run the same manufactures tyres front and rear. Is this true ???? and if so why ? No one here can give me a good reason that makes tecnical sense to me.

The clear question is can I run different tyres on the front and rear and if not why?

[ar38070]

The only definitive answer is to try it and see what happens. If you like the results great. If not now you know.

However before you try this you may want to experiment with tire pressures. If you were running the pirellis and the michelins at the same pressures then you need to experiment with pressure changes first. It is unlikely that the two tires would run "best" at the same pressures.

[johnnys]

Thanks for the reply,

I have been doing this and the results are great. I run the rear michelins at 44 and the front pirelli's at 36.

The question is why do the manuals say to run the same manufactures tyre's front and rear ? anyone know. ? That as they say is the question.

Just to clearify I have both front tyres as pirelli and both rear tyres as michelin.

[Loren]

Thanks for the reply,

I have been doing this and the results are great. I run the rear michelins at 44 and the front pirelli's at 36.

The question is why do the manuals say to run the same manufactures tyre's front and rear ? anyone know. ? That as they say is the question. 

Just to clearify I have both front tyres as pirelli and both rear tyres as michelin.

From the "Approved Tires and Wheels" TSB.

If new tires are to be mounted or the tires of one axle are to be replaced, tires of the same make, the same type and with the same specification code must always be used on each of the two axles. If tires are replaced on one axle only, the different tread depth from that on the other axle can cause a noticeable change in the familiar handling. This is especially the case if new tires are mounted on the rear axle. This effect decmases with increasing tire mileage.

My guess is that it is a legal liability issue for Porsche (i.e. Ford Explorer/Firestone tires).

[johnnys]

Thanks, I fully understand the "tyres of the same type and with the same specification code" but its why "the same make" thats I want to know about.

[ar38070]

It is all legal mumbo jumbo. Just like you are not supposed to patch a tire. As far as mixing brands as long as you understand how the car handles with mixed tires then as long as you are comfortable with it then do it.

[dlipka]

I have just bought a '99 C4 - It has 18" wheels fronts are 225/40 rears are 285/30 where sticker under the hood suggests that they should be 265/35. What impact would this have on the rolling diameter / 4WD system? Or are they actually the same rolling diameter?

Hope that someone can help me.

Derek

I drive back roads In New Zealand very hard. I drive a 996 C4 2002 The roads here are very rough.

I found I get 7,000km from a pirelli pzero rear tyre and 15,000km from a front tyre. alternatively I use michelin pilot sports. I get 18,000 km from a rear tyre and 25k km from a front.

I find if I run the pilot sports front and rear the PSM cuts in a odd times on the front wheels as the tyres dont have the same grip as that of the pirelli's. This happens at high speeds on uneven roads and can be very unnerving. it only happens with the pilot sports and not the pzeros(on the front)

So what I did and would like feed back on is I am running the PZero's (pirelli) up front and the Pilot sports on the rear(michelin). This means they wear at the same rate. I also get the front end grip I need and can also accerate hard without nearly hearing the rubber wear off the rear tyres (as when I run pirelli on the rear after every drive I measure the tread and for a good run I lose nearly 2 mm)as the michelin at the back are harder.

Now all the manuals I read and car mags when they do tyre reveiws say to always run the same manufactures tyres front and rear. Is this true ???? and if so why ? No one here can give me a good reason that makes tecnical sense to me.

The clear question is can I run different tyres on the front and rear and if not why?