Help - Need New Tire Advice - anybody gone taller?

[gsrhoden]

Not having been on the board very long either, I will be the first to welcome you. Hopefully the response you got was done tongue in cheek but maybe not. I am sure you are not alone in your desires. Not all of us are obviously boy racers looking for that ultimate balance of handling and speed. If you are like me, you got the car because you can appreciate a well put together automobile that is more enjoyable to drive than your typical standard sedan. I can also appreciate your desire for some extra "cush" in the ride. I have several patches of terrible road surfaces on my way to work and it really rattles through the car. I also fear that some of the potholes may eventually overcome the low sidewalls and damage either the tire or wheel or both. But such is the compromises that are expected when owning a car like this. While increasing the wall height on the tires will obviously affect the handling, it is your choice on whether you can live with it or not.

If I had known that it was sacrilegious to not drive the car like a bat out of hell all time, I would have kept my ownership more of a secret .

Good luck with the car.

[stephen wilson]

My WAG is that your profile change won't cause any problems. Plenty of people have gone from a 265/40 to a 275/40 without issue, though this is a much smaller change in diameter.

One alternative might be a less performance oriented tire, such as an all-season tire, with softer side walls. Tirerack.com has ratings for ride comfort.

[dr_gille]

Thanks for the welcome gsrhoden - in regards to an earlier post. I appreciate it.

I honestly think I'm going to pursue this for a while.

The naked truth is, the job of a tire is to stay in contact with the road. Unless
one is on a billiard table smooth skid-pad, bigger wheel and tire combinations
(+1, +2) will negatively impact performance in every measurable category
EXCEPT braking, and only if the reason for the move up was to install larger
rotors.

And/Or/If one spends Cubic Dollars on very light wheels and carbon ceramic
rotors. There are some especially deep pocket folks out there that can drop
$10 to 20k on brakes and wheels, but my budget is a tenth of that.

Larger wheels and tires are heavier. They have a greater flywheel effect
which requires more energy to spin up to speed, and then stores more energy
that has to be scrubbed off when slowing down, meaning extended stopping
distances, and increased brake wear.

There's also the increased gyroscopic effect of those four flywheels spinning
(which you really can't feel on a car that easily, but if you've been on a
motorcycle, the effect is obvious).

This gyroscopic effect of stored energy provides a net resistance to the car
changing direction. That impacts the nimbleness of cornering.

No Spin - No Proof. In many ways.

I darn near spun it last week, hooking into a corner and downshifting, and I
hit very small pressure ridge in the pavement, which the hard sidewall low profile
tires skittered across and the rear end broke loose.

Almost pulled a Speed Racer, headlights/tailights/headlights move.

I was surprised, because that Never happens in my Electra 225 (haha, just
messin with you guys...)...

[mikefocke]

are an endlessly debated topic.

Go feel those rear Yokos. Bet they are cupped (irregular wear on the tread edges). Also they are known to be noisy when worn. Had a set, hated them, couldn't wait to get rid of them. Measured the decrease in noise by how many notches I was able to turn the radio down...4.

I wouldn't change tire size, just change to new tires and get a professional alignment done by someone who really knows how to set up a Boxster to favor even tire wear but still within Porsche specs. The idiot will set up to meet the spec but won't know what end of the spec to favor to get results. The really good alignment person probably sets cars up for racing and so understands the influence of the various measurements. Can double your rear tire mileage.

Three brands/models are constantly mentioned. Michelin PS2, Sumitomo HTR Z III and Kumho Ecsta SPT. They all make high performance summer radials to fit a Boxster with 17" wheels. The Michelin's are the benchmark against what tire testers test other tires but are expensive. If you buy them, make sure of the model number if you want the Porsche approved/tested version of the tire, it is slightly different from 3 other model numbers advertised under the same marketing name. The other 2 brands (Sumi/Kumho) are significantly cheaper.

Every tire has its proponents.

[stephen wilson]

Hmm... were you downshifting while "hooking" into the corner? ( sorry, I'm not sure what that phrase means )

[landrovered]

Gilly,

You forgot one benefit of taller sidewalls, they have a built in audible sensor to warn you of impending traction failure. More rubber equals more warning before you go assooverteakettle around some corner. 35s are not quite as friendly in this way.

I love your sense of humor, stick around and sooner or later we can BBQ some of the sacred cows that seem to be grazing this forum.