18x8 ET 57 with 245/40/18 and 18x9 ET 43 with 285/35/18 - will I need spacers?

[KRAM36]

Have you already bought the tires? I hear 245 are a bad size for the front of the boxster for street use, they tend to follow road grooves really bad.

A better daily driver setup would be 235/40ZR18 275/35ZR18

[stephen wilson]

Originally Posted by KRAM36

Have you already bought the tires? I hear 245 are a bad size for the front of the boxster for street use, they tend to follow road grooves really bad.

A better daily driver setup would be 235/40ZR18 275/35ZR18

Not true, I put 245/40's on my 987 and didn't notice any increased "tramlining" than with the 235's.

[KRAM36]

Originally Posted by stephen wilson

Not true, I put 245/40's on my 987 and didn't notice any increased "tramlining" than with the 235's.

I should have been more specific. I've been told this about the 986 model, your 987 has electric steering.

[stephen wilson]

Originally Posted by KRAM36

I should have been more specific. I've been told this about the 986 model, your 987 has electric steering.

Nope, 987's have the same old Hydraulic steering as the 986.

[KRAM36]

Originally Posted by stephen wilson

Nope, 987's have the same old Hydraulic steering as the 986.

My mistake, thought I read it did.

The person that told me this was Johnny Danger when he gave me his number to call him about wheel and tire setup for my car. He has run a number of combos and he said not to go 245 in front because of the "tramlining".

We where talking the 986 though. Maybe Porsche changed something in the 987 that reduces "tramlining".

Even with my current 225's in the front I get some "tramlining", will 235's I'm getting be worse, guess I'll find out.

[husker boxster]

The 981 has electric steering.

[woodsman]

I think tramlining is dependent on the tire itself- ie the strength of the corner where the sidewall and the contact patch meet.
Regarding rim widths what it comes down to is support of the tire. Where you are in the approved rim width range effects the shape of the contact patch which effects how the tire performs and communicates. If you never get to the limits of adhesion this matters less but an oversize tire will tend to feel numb- like wearing oversized winter mitts. The car will also feel heavier.
Then there's scrub radius. That's the arc the wheel passes through as you rotate the steering. Offset effects this and can change how the car steers. I ran a 17mm spacer on the front of my car with stock 18*7.5*50 and the steering was abrupt and too sharp- it looked perfect but it wasn't worth the loss of precision to me.
Just saying there's a lot to consider when we stray from how Porsche set things up and we often discover unexpected consequences. But then that's how we learn isn't it? Play on ...