tar6day

I have a 1997 993 tt with 265/35 x 18 frt and 315/30 x 18 rear MPSC's. They are mounted on 9" wide frt and 11" wide rear Forgeline rims.

What would be a good rain tire that could fit on that wide of a rim?

I am going to buy an extra set of rims, not sure what offset to get, so I could maybe go with a more narrow rim. I think it would make things easier if I keep the extra set the same width?

Does anyone have a guess on what the offset would be on my Forgelines? It is not marked anywhere on the rim!

Thanks ,

Tim

gooseNSJ4

I just bought the Michelin PS2. Have not had the chance to try them out yet, but I hear that it is a great tire. I know they come in 265/35/18 but the rear comes only in 295/30/18. I run 235/40/18 and 295/30/18 with HRE wheels and offset of 47 front on 8.5 wheel and 49 rear on 11 wheel. The Michelin PS2 would fit the size of your rims. In any event the wider tire you go with the more problems you will have with the rain issue.

Regards.

993tt

Just a little advice if you didn't know about this already.

The rear wheels diameter should always be smaller than the front wheels (even if the front are completely worn out and the rear are new) due to the viscous coupling. This means that the rear will always turn faster than the front and thus always transfer power to the front.
I don't know what happens If it's the opposite but I bet it's nothing good.

I been checking for different tires than N2 but it's very hard to find a set that fulfill these requirements.

/Erik

///alpinepower

does anybody run toyo T1-S? I liked them on E36 M3 and 993 C4S

Viken

Why?

993tt

Because of the way the viscous coupling works. If the rear turns faster than the front the coupling will transfer a little power to the front. If I remember correctly this should be 5% under normal conditions. If the front turns faster than the rear, I don't know what happens but there will be no power transfered to the front i bet. A guess is that the front will steal power by working against the engine. But I could be way off...

This is how it was explained to me by a Porsche mech and I think it sounds sound.

/Erik

HBdirtbag

or try the proxes 4's, almost as grippy as the T1-s's but awesome in the rain and light snow

Steve Weiner-Rennsport Systems

I'd offer that the Dunlop SP-9000's are superb rain tires.

Living here in the PacNW for the past 50+ years, I've never used anything as good........

graham_mitchell

That doesn't sound right to me. The VC should start to lock up under any difference in rotation speeds, regardless of which axle is rotating faster.

993tt

Maybe nothing bad will happen to the transmission but since the VC is a stupid thing it will only transfer power if the rear spins faster then the front. If the front spins faster then it should remove power from the front, right!? At least, that's as much as I can figure out.

What I was saying is that if the wheels are not the correct sizes no power will be transfered to the front during normal conditions. Porsche meant the front to get at least 5% power when the wheels are new and (I guess) just around 0% if the rear are new and the front are completely worn out.

Been thinking about it and I guess that if the front wheels turns faster than the rear, let's say by 5% because they are too small then that would mean that the rear have to "slip" 5% before the front starts to get any power, right? Compare this to the configuration the car comes with from factory where the front always gets 5%. Wouldn't that be much safer if you start to slide during, let's say a take over!?

I don't know how it feels or if it's dangerous in any way if you have the wrong sizes on your car but logic says that it's better to have power come sooner to the front during extreme conditions than half a second to late. These cars can still snap on you... Or, maybe it would just mean a more entertaining driving experience

/Erik

Mark in Baltimore

If you're looking for a rain tire for the track, full tread Toyo RA-1's seem to get wide praise on the racing and drivers ed board. I have a set for my 993 but have never had a chance to use them on the track.

The MPSC's are a bit squirrelly in standing water...

JJayB

The Pirelli Corsas" with a 235/40 and 295/30 will be the proper size and diameter for your wheels. They are rated excellent in the wet. I would venture to say you will kiss your MPSC good bye after driving this set up.
IMHO, I've found the Pirelli's to be faster tire than the MPSC and you will have solved the understeer problem inherent with running a larger diameter rear tire. No VC problem with this combination.

KRA993tt

Abalto,

Where were you this weekend? I was the only 993tt at SP and 142 through the chute is well beyond me. FWIW I use SO2's they came with the car.

KRA993tt

I look forward to meeting you next season. Happy New Year!