phantomias33

I've tried to do some reading and education myself on tires. The site I found most useful was:

http://www.1010tires.com/tiretech.asp#sizing

I think I want these:

http://www.michelinman.com/catalog/t...etype=5&tire=5

It's the Diamaris by Michelin and I was hoping to get it in the following size: 315/35R20 and they're W rated tires.

However, they say that it needs a rim size of 10.5-12.5" and Porsche only sells rim widths of 9 inches, so guess I'll have to get rims elsewhere. (sucks, because I wanted to get the color logo in in the center of the wheel...oh well.)

Anyone have other suggestions for tires? I was thinking "wider is better", hence the 315 width size of those tires (they make a 275 and a 255 width size as well.)

For those european members-> know a good place to get this done? I live in South Germany.

Thanks

Jeffrey Behr

The Diamaras are W (168MPH max.)-speed-rated SUV tires designed for summer/hi-performance use. Based on the gillions of threads about horrible performance in the snow of original-equipment Cayenne tires, they're apparently quite poor in the snow and mud. If you never expect to take your C off-pavement and do expect to drive it at speeds in excess of, say, 150MPH/242KPH, then this summer/hi-speed tire is quite suitable. I do recall several notes about quite-poor life of these tires.*

I drive my C-T hard and sometimes fast (see this), but I installed SUV tires that are rated at 'only' 149MPH/240KPH. They're Toyo Proxes S/Ts; see here. Unfortunately they don't have a size you seem interested in.

I suggest you also consider the Kumho Ecsta STX here and the Hankook Ventus ST RH06, here.

I believe if you want to go with substantially wider tires, you'll have to buy wider wheels. Let us know what you end up doing.




* Sort of reminds me of an article I read about the Carrera GT...that the development drivers and engineers were quite happy to see one set of its specially-developed-and-I'm-sure-VERY-expensive Michelins last 800 miles!!!!!!!!!!!!!!!!!! They also said that they expected a set in customers' hands to last upwards of 10,000 miles/16,000KM.

Now think about this--the factory-recommended oil-change intervals are the same as the Cayenne's, that being 20,000 miles/32,000KM. That means one can expect to consume and replace a set of tires in HALF the time the oil 'wears out'. I guess those who spend over $400,000 for a 'car' think differently than us regular folk.

And this reminds me of the 'Car and Driver' article about the Ferrari Enzo. It requires 15 quarts of oil that costs $60/quart. That's NINE-HUNDRED dollars (plus filter, plus labor) for an oil change. My my...

k2kv

Wow, Jeff,

You did 150 MPH on those Toyos?

Now THAT must have gotten your heart beating pretty fast!!

I'm jealous - - looks like fun...

Jeff

phantomias33

You know...perhaps I ought to consider something else. My wife is actually buying the car and she was thoroughly impressed when she went to wider tires on her Audi S4. Anyway, perhaps that's a bit extreme and considering, she won't be driving that 'bat-out-of-hellish', something else may make more sense.

I looked at your stretch of highway that you posted (Highway J1), man I'm envious. I live in Germany, but this whole assumption about the autobahn is a load of sh*#; most of it is speed limited to around 130 kph. Certain sections you can open up your car, but you're constantly slowing down and then speeding up again.

I'll check out those other tires you recommended. What size are yours? Sounds like you were able to get quite aggressive with them, eh?

Incidentally, I will be getting some 18" rims and accompanying tires for winter.

Harbormaster

Hi.....Did you know that Porsche specifically recommends several different tires for specific wheels and applications ? These are listed in a coffee table book "Cayenne". I'm away from my home now so I can't give you anymore info than that now.....however, I may have provided the name and publisher of the book in previous days on this site. The book itself is sold for $62 but can be bought on Amazon for about 37 and it is a bargain at that price. That's not say that there arent other combos guys have had success with but it's a good start.

Harbormaster

The info on that book I mentioned is contained in a thread "New Cayenne Book" started by me on 2/26/04. Use search to find it if interested.

phantomias33

Hey Thanks Harbormaster....I'll look it up. I'm progressively becoming more knowledgeable about cars in general. First looks mattered. Then the interiors. Then Horsepower and shortly thereafter torque. Anyway, my education has finally brought me to tires and I'm playing catch up. I'd hate to have my wife spend that kind of money for a Cayenne T and have cruddy tires. So I'd just assume get some nice non-winter ones for her so it's never an issue of "well, too bad you didn't have nice tires."

Jeffrey Behr

phantomias, my tires are 295/45R20s on 20X10" wheels with a 7.2" backspace. The tires are 30.4" tall, larger than all the original tires which are 29" tall.

If I had to do it again, the wheels would be 9.5" wide; they're close enough to the outside edges of the tires that they get dinged when crawling around in Colorado...see here.

The taller tire increases ground clearance everwhere about 3/4", which is good, but they also make the speedometer about 5% slow, which is not good but is something I can easily live with.

plianides

I got a Cargraphics catalogue, and they list quite a few wheel size options for the Cayenne. I don't have it in front of me, but you can probably find something that will fit 315MM in the rear.

Personally, I have the Techart 20x10s - with the stock 275/40/20 tires.. When I replace my current tires, I will bump up to 295/40/20s front and back...

phantomias33

Jeffrey Behr,

Nice looking tires. I checked out your pictures on webshots. I wouldn't be looking for tires to do what you're doing, I'm just thinking that "wider is better" for grip and cornering on roads. I like the width of what you've got on there, I'll probably try and find something similar.

Raptor

For what its worth (with due respect to those who already know this), the tire height can be determined by multiplying the first two numbers together and multiplying that product by .000787 and adding wheel diameter, For example, the height of Jeffrey Behr's 295/45/20 tires (at rest) is equal to (295 x 45 x .0007874) + 20 = 30.45 inches. The height of pilanides' 275/40/20 is 28.66 inches and the height will increase to 29.29 inches with 295/40/20 tires. I don't mean to be ****, but I have learned so d----d much from this forum that I wanted to share what others may not know of this conversion. Incidentally, the reason Jeffrey's speedo is off by 5% is because the height (and therefore the circum) of the larger tire at 30.45" is 5% greater than the stock 255/55/18 at 29"