275/40's all around on 95R

[boogie]

Anyone know if 275/40s will fit ok on the front? I'm pretty sure they will fit on the back, but I'm not sure on the front.

:shrug:

 

[juicedgt02]

Good question:beer: as I am getting some 275/40/18s put on my 02 GT. I was told that it would not rub, but thats not an sn-95, so I am not sure aboutyour car, sorry. Good luck thou:thumbsup:

 

[Cobra-R]

Yep, they fit no problem. I run them on the track with the car lowered.

 

[Cobra R Man]

275/40's

Originally posted by Cobra-R
Yep, they fit no problem. I run them on the track with the car lowered.

me too!

 

[CobraR77]

I run 275/40s on both my 95R and 95TwoTop w/ Eibach Pro-Kit springs. On the R they rub the inner fender liner ever so slightly when the wheel is locked. I think the combination of the race alignment, lower then stock springs, and the unshaved Toyo RA-1s (these appear to run a bit bigger then my KD-Ws and Nittos of the same size) I run on the R cause this. I wouldn’t hesitate to run this size of tire.

 

[jwfisher]

I'd suggest you do hesitate... once your lower control arm bushings start to wear you'll get (eventually) several inches of side-to-side movement... and the wheels will HIT the inner and outer fender edges. Even Ford knows this.. it happened at Nelson Ledges during their own test sessions.

Solid axle cars don't work with tires this wide without panhard rods.

 

[boogie]

Interesting. The 275/40s are standard equipment for the 03 cobra. Is there more clearance with the new-edge style vs. the sn95?

 

[Cobra-R]

Originally posted by jwfisher
I'd suggest you do hesitate... once your lower control arm bushings start to wear you'll get (eventually) several inches of side-to-side movement... and the wheels will HIT the inner and outer fender edges. Even Ford knows this.. it happened at Nelson Ledges during their own test sessions.

Solid axle cars don't work with tires this wide without panhard rods.

Hmm, very interesting!!! My car does have a phb and everything else is mounted solid with no rubber bushings remaining.
Good point, jw. :beer:

 

[jwfisher]

Originally posted by boogie
Interesting. The 275/40s are standard equipment for the 03 cobra. Is there more clearance with the new-edge style vs. the sn95?

The problem is with the solid axle moving side-to-side. It's such a terrible design that as it wears it moves more - considerably more. I've seen worn examples actually sticking a few inches out of the fender in turns on racetracks! And then, of course, there is a rear steer effect anyway, not to mention the huge unsprung weight.

IRS doesn't - can't - have this problem. There are other issues, but this isnt' one of them.

Take a look at this article on my website for more information and a picture of the resulting damage to the rims and tires.

Also, to answer your other question, tire clearances are slightly different in "new edge" cars... front and rear. The wheelwells have changed. The front control arms have changed a bit. But, also, the solid axle 8.8" cars have a wider rear track (axle) by a tiny bit too. You won't find a hard stop with off-the-shelf Cobra R 17x9 wheels, in fact there now adaquate room for 275s up front (roughly equiv to a 94-8 with export flares) on these wheels. As always, watch offset very carefully.

 

[boogie]

wow, great article.

I didn't realize the axles could move that much during a driving event. Do you think I would be ok with the 275s for street driving? I guess I'm thinking that for the street, it would not get the stress that it would get on the track. The LCAs were recently replaced with MegaBite Jrs. Then I would use 255 or 245s for track use.

 

[Cobra-R]

with as much movement as he mentioned on that page, I would think even the 255's would rub on the track.

 

[jwfisher]

The axles sure will indeed move that much, once wear sets into the bushings. Then it's really bad. I've had a wheel destroyed myself that way over the years (I've been open tracking Mustangs since '80).

And, it's as much the width of the wheel as it is the tire size. If the wheel/tire is jerked over into the wrong place, either will hit and it could very well be a disaster. If you catch it before it destroys the rim or the tire, then atleast you might be able to drive home. But, your weekend is still wrecked.

 

[jwfisher]

255 what? 45 or 40? That's the problem... 40s are too short, 45s are taller than stock - which isn't necessarily bad. But, in either case, you've got to have a 9" wheel to support them.

There is even a school of thought that feels that 255s on a 9" rim handle better than 275s on a 9" rim - because of sidewall profile differences. I say it's more complicated than that.

You have to take a look at it at a higher level... is the total suspension designed to work best with a high profile tire or a low profile tire? The simple answer is that given our front strut suspension, on near-stock tuning, the car will roll and a higher profile tire will work better. But, it's more complicated than that. Even without much roll, it's been shown that there are reasons to retain some profile, at least.

After years of working with a suspension and platform that is less sophisticated than a new Explorer (which is all independent, SLA, coilover for gods sake!), I'm not interested in anything less than all-independent, SLA, and coilover on the upcoming all-new Cobra. I have no inside information, and I couldn't share it if I did, but I am beginning to fear that necessary cost cutting may not result in a car that has the suspension I want. I'm sure the rest of the car will be way better than what we have now (certainly far better chassis integrity, NVH, quality of construction and materials, and some weight balance improvement)...