Bigger rear tires on 99 C4?

[bnewport]

It's time to change tires. Anyone know any reason why putting 280/30 tires on my porsche 18" rims is a bad idea? The newer 996s came with these tires on the same rim. The car currently has the 225 and 265/35r18s on.

Are there any issues with suspension or other adjustments when I put on these tires. Any warranty issues etc?

[NickS]

It's time to change tires. Anyone know any reason why putting 280/30 tires on my porsche 18" rims is a bad idea? The newer 996s came with these tires on the same rim. The car currently has the 225 and 265/35r18s on.

Are there any issues with suspension or other adjustments when I put on these tires. Any warranty issues etc?

<{POST_SNAPBACK}>

you can go with 285/30-18 on a 10" wide rear wheel. I don't see the need for anything bigger with a C2.

[Loren]

On a MY99 C4 you can certainly go with a 285/30 x 18 rear tires - but that will increase understeer even more more in a car that already has quite a bit. A better solution (IMHO) would be to also change the front wheels to an 8" wheel (originals are 7.5"). This alone would bring the cars understeer balance back to near factory spec. If you want to reduce understeer even more then use a 235 or 245 tire on the 8" front wheels (standard is 225).

[bnewport]

The dealer is talking me out of it. Current plan is to stick with 265r30s. He says the C4 is picky about circumference and I'm risking my tranny screwing around. Any comments?

[Loren]

Hmm... what would they say to the fact that starting in MY02 all C2 and C4's (except C4S) had 285/30 x 18 (on 10 inch wheels) rears and 225/40 x 18 fronts (on 8 inch wheels)?

I've had both on my MY99 Coupe for 5 years.

[clord]

bnewport.... Your dealer is correct...but, so is Loren. I had a '99 C4. For 40K miles I ran 8"s and 10"s with 225/40-18's and 285/30-18's with no problems. Have a look at the revs per mile for those two sizes of tire for the make/model of tire you expect to get....and, if they are within 2% of each other...you are good to go.

[P.Viby]

Well I drive around with 295/40-18 on the rear. That is okay, and it looks **** cool. BUT I will change then back to 285 next time. Not quite sure about how an insurence company would look at it if something happens.

[Dr. Carrera]

Having recently purchased a set of 8" and 10" Carrera Rims I schedule to fit them on my '99 C2 with tires in sizes 225 in front and 285 rear. My dealer confirmed me there's no problem whatsoever. I note also that in Porsches factory Tequipment brochures these rims are offered with those tire sizes for all 996 C2 and C4 Porsches from MY 98 till MY 04 :drive:

On my 'old' Turbolook I rims I currently have Conti Sportcontact2 in sizes 225 in front and 265 rear. I intend to "finish them" on a trackday soon. Afterwards I will fit the Carrera Rims but I'm still not sure what tire brand to purchase <_< It should be the best compromise between everyday use and track-day usability. How do Conti, Michelin and Pirelli compare in that respect? Any experienced advise would be welcome :jump: .

Edited April 5, 2005 by Dr. Carrera