Fuchs 8" vs 9" question

edward993 · 10-05-2005, 10:42 AM

Just wondering from those who have gone froms 8s to 9s in the rear.

I can barely tell the difference visually, if at all, between the two, but is there any noticible difference in "stickiness," especially on the track? Assuming the same tires and size, is there a considerable improvement, or is it more subtle? Thanks in advance, all!

Edward

stv951 · stv951's Garage

I 've done that, and you are right. There is not much visual difference. Tire wise, my 8s had 225s whereas 9s have 245s

Wayne 962 · Wayne 962's Garage

It's bragging rights. Like H1s vs H4s...

-Wayne

stv951 · stv951's Garage

Any detailed pics of both ?
Here are some 9x16

[img]
http://forums.pelicanparts.com/uploads6/fuchs+9x16+new1128539426.jpg[/img]

89911 · 10-05-2005, 11:15 AM

I'd have to agree, its the 245 of the rear that helps. Unless your going to go with a 225 up front ( with a 8"951 rim) then a better balance might be the 205-225 set up with 7's and 8's.

KobaltBlau · 10-05-2005, 11:25 AM

What? you don't need 9s to run 245s.

KobaltBlau · 10-05-2005, 11:38 AM

How? For the Toyo RA-1 DOT R tire I like to run in 245/45-16 the recommended wheel width is 8".

I know the racer's argument about sidewalls being more stretched out and that being somehow better but I think the tire manufacturer's recommendation is good enough for me.

edward993 · 10-05-2005, 12:06 PM

Thanks for the input, all ...keep it coming.

But I have run 245s on my 8s with no squirreliness whatsoever. In fact, it feels really planted on the track (w/205s on 7s), and this with street tires, not r-compounds. Agreed that 9s would be better for 245s, which is why I asked the question in the first place. But if you look at 245s on 8s, there is no bulging, and the sidewalls "seem" pretty well supported. I was just wondering that given the same 245, is there a marked improvement with the 9? Thanks!

Edward

Bill Verburg · Bill Verburg's Garage

Quote:

Originally posted by KobaltBlau
How? For the Toyo RA-1 DOT R tire I like to run in 245/45-16 the recommended wheel width is 8".

I know the racer's argument about sidewalls being more stretched out and that being somehow better but I think the tire manufacturer's recommendation is good enough for me.

Once again the measuring rim has been mistaken for the recommended rim. Toyo has a recommended range of rim sizes. for the 245/45 x16 RA-1 comp radial this is 7.5" - 9", what they don't tell you is that max performance from a given tire will almost always be obtained by using the widest wheel in the recommended range. This last tidbit is a fact not a fairy tale

KobaltBlau · 10-05-2005, 12:26 PM

Quote:

Originally posted by Bill Verburg
Once again the measuring rim has been mistaken for the recommended rim. Toyo has a recommended range of rim sizes. for the 245/45 x16 RA-1 comp radial this is 7.5" - 9", what they don't tell you is that max performance from a given tire will almost always be obtained by using the widest wheel in the recommended range. This last tidbit is a fact not a fairy tale

OK Bill, I was not aware of this (obviously). Can you characterize the difference in performance between a 245/45-16 DOT R tire on an 8" rim versus the same tire on a 9" rim? Thanks in advance.

stv951 · stv951's Garage

Abit OT, but should I add 14mm spacers on the rears ? Would widening the track decrease oversteer ?

Bill Verburg · Bill Verburg's Garage

The wheel has geater leverage on the tire carcass, the sidewalls are effectively stiffer, the tread squirms less, the tire runs cooler and at lower slip angles. These are all good things from a performance perspective.

The bad side(to some) is that the ride is harsher.

there have been many back to back timed tests of this concept

Jack Olsen · 10-05-2005, 12:32 PM

Nines are obviously better. But how much better, in practice, is a valid question. I've driven both, and the differences weren't noticable at all to me. In a race between a car with 245's on 8's and one with 245's on 9's, it'd likely be other factors that would make one car faster than the other.

stv951 · stv951's Garage

Thanks Bill,
should I increase stud sizes for these 15mm spacers ? or they will have enough threads to be safe ?

KobaltBlau · 10-05-2005, 12:35 PM

OK, what you say makes sense.

Quote:

Originally posted by Bill Verburg
there have been many back to back timed tests of this concept

Where? or what do I search for. very interested.

Thanks,

petrolblue83911 · 10-05-2005, 12:38 PM

Doesn't it also seem that it depends on the tire mfg?

-I had 255's on the rear of my 928s4 on cup alloys (9 or 9.5 wide) with AVS sports, and i swear they looked narrower than my previous 245's which had been dunlop sp8000's on the stock phone dials, it was more of a visual thing, but really, they looked narrower than the smaller tires??

Bill Verburg · Bill Verburg's Garage

Quote:

Originally posted by stv951
Abit OT, but should I add 14mm spacers on the rears ? Would widening the track decrease oversteer ?

wider rear track will increase oversteer

Bill Verburg · Bill Verburg's Garage

Quote:

Originally posted by KobaltBlau
OK, what you say makes sense.

Where? or what do I search for. very interested.

Thanks,

I think that Grassroiots my have done one recently. Some of the tire manufacturers have published this info, Michelin for sure.

KobaltBlau · 10-05-2005, 12:44 PM

ok, I will try to find those. thanks again, Bill.

carrera1975 · 10-05-2005, 01:08 PM

One other small factor should be noted, If you have a limited slip and you go with 245's they will really grab out of the tight stuff, especially when get on it early, which will make the car want to go in a straight line not good on the street. I have 7 x 16's and 8 x 16's with 225 50's with my 60% ZF, I tried 245 and it flet like a swamp buggie with the front wheels in the air cranked the in opposite direction