CorrdoBrit

Removed the 7mm spacers on the rear and installed 285/30 18 Bridgestone S-04 tires on the Enkei RC5 rims. Love the look. Very of the period. The profile has given me an additional 1cm of gap to the fender and no rubbing. I would say the online tire calculators were pretty close in this case.

nile13

I _really_ do not understand the combination of a wide and not very sticky tire.

CorrdoBrit

Well in terms of width the 285's are right in the middle of the recommended range for a 10" wheel. No stretch and not oversized in the RC5 rim. As for stickiness, I have no intention of racing so ultimate adhesion is less of a concern.

nile13

285 is not a great size tire for a narrow body 993. Of course, depending on your front tires and suspension setup. So, if your fronts are 225 (?), why go with 285 on the rear?

I would also question running a fairly soft sidewall tire on 30 ratio. In short, I'd go with 225/40 and 265/35. Wait, that's what I did (with a stiffer sidewall tire).

RC5 is a good rim. Nice looking an light.

Mark in Baltimore

I had to roll my rear fenders when I ran 285s in the rear. Got rubbing on the oil line, too, under track conditions (have no idea if rubbing would have occurred on the street). This was with my correct-offset Fikse FM-10s.

CorrdoBrit

Yes, I'll keep an eye on oil line rubbing. So far no odd sounds inside the cabin when cornering or hitting uneven surfaces. Whats the offset for the Fikse's? The RC5's are ET60.

Sure 225 would not have been my choice either but they were installed by the previous owner and practically new so will keep them for now and replace with a wider track tire at some point in the future.

Mark in Baltimore

8 x 18 and 10 x 18
51mm offset front, 63mm offset rear

CorrdoBrit

So that would push the rim and tire a little closer to the inner fender wall and increase the chance of contact with the oil lines. Hopefully ET60 gives me a bit more room for movement enough to avoid rubbing under compression.

Matt Lane

285/30 is a smaller OD tire - helps vs. exacerbates the tall gearing (if not the spacing between gears). A 235 front fits, so I would pair with that.

For comparison from my current setup

- a 265 on a 10 inch rear is undersized (Sumi on OZ)

- a 275 (taller) on a 10 inch rear fits fine (NT-01 on BBS E88)

Now that the 993 has been decommissioned from track, I will try whatever looks best without rubbing. On street, no one will notice a bit of difference.

Cheers

Matt

nile13

Don't. You are trying to make the car undriveable on the street.

BTW, on a separate note, check if you have a steering rack brace installed.

nile13

1.5mm closer. That is 1/16", so of no particular relevance (hit a big enough pothole).

Matt Lane

This can't be a serious post?

The OP is not trying to make his car undriveable.

The 225 tires are new, good quality, and factory size spec.

If you are actually experiencing under or oversteer on the street such that the car is truly undriveable, your are driving too fast.

Am I missing something?

Cheers

Matt

nile13

It is 100% serious. I believe that going to wider tires "because they look good" is a way to make the car tramline, be less responsive on turn-in and we can discuss a number of other side effects.

I'm sure that any car can be driven with any round tires pointed straight... at some speed. Why make a 993 into that - I don't know.

PS. No, increasing the width of a front tire by 10mm at a time is not making the car undriveable. The point is about the (lack of) direction to the "upgrades".

Matt Lane

Was not looking to be argumentative, just helpful to the OP.

265 is a stock width and 285 is .78 of an inch wider than stock.

Stock F/R stagger (all things equal on suspension, not to be assumed on a 20 year old car) has built-in understeer.

3/4 inch more rear tire adds to the understeer.

If you are driving n the street, you really should not be driving so fast as to induce any understeer (in my personal opinion). If you drive in snow, sand, rain or on the track - that's different and outside of this discussion.

A 993 will be perfectly safe, driveable, and enjoyable on a 225/285 setup in street usage. Not ideal, but I don't think discarding new front 225 tires makes any sense. 235 would be better, 275 good too. Depends what is available and not worth the drama (again, just my opinion).

Cheers

Matt

_snowbird_

I also don't get the perspective about 225/285's compromising the car's handling. This is the stock tire size on my C4S.

I know the NB 993's call for a narrower rear - which I assumed was simply because that was the max space (comfortably) available on a NB in stock trim. But given that the C4S has the same engine as a C2/C4/C2S, why would Porsche have specified 285's in the rear?

FWIW - I'm going to be adding a bit of width to the fronts (to 235) for my next set of DE tires.