Yet another tire thread. 325/30r20?

[Pribilof]

Yet another tire thread. 325/30r20... YES!

I've searched for days and can't come to a solid conclusion so I'm asking for help.

It appears that yes, 325/30r20 is possible to run without much work on a 20x11 rim. Any ideas on backspacing? 53? 55?

Also debating running 19x11s in back with a 325. The tradeoff is a slightly shorter tire, which I'm not sure I like with the 3.73 gears.

I'm not sure I like running a DR all the time so I was planning on trying out the Michelin Pilot Sport Cup 2 tires. These are a "bargain" at $350 each in the 325 size versus $535 for the 285 size :shrug:

 

[DutyCalls]

here ya go

http://www.svtperformance.com/forum...d-up-the-badass-TVS-Forgestar-325s&highlight=

 

[Pribilof]

Wow thanks. Not sure how I missed that thread.

 

[DutyCalls]

if thats not wide enough check out my 335 tire thread.

http://www.svtperformance.com/forum...5-335-30R20s-on-custom-widened-Forgestar-F14s

 

[enormous]

I run the 325 30 20 Sport Cup 2 on a widened 11.5 rim without rubbing and my two friends run the 325 30 20 on a 11" and 11 1/4" rim.
A 325 on a 11" rim fits well and does not bulge.
A rim fitting as far outbound (toward the fender edge but not sticking out is important) is critical to fitting a 325 tire under a Shelby.
A spacer and longer wheel studs may be required position a rim as far outbound depending on the rim backspacing.
My Custom Boze Tach rims were widened from 10" to 11.5 and no spacer was required.
My friend widened his 20" 2011 rims to 11 1/4" and required longer studs and a custom 7/16" spacer for ideal fitment. Here:
http://www.svtperformance.com/forum...-11-25-quot-wearing-325-Dunlops-Job-completed

I believe I have photo's in a prior thread on this forum also.

 

[Pribilof]

These were not easy to find. Going on next week. MP Sport Cup 2. 325/30/20.

 

[Catmonkey]

If you do the math on some of these widened wheel cobinations, you'll see that they're in the 57-62mm offset range. Less than 57mm and you push the tire further outboard and may contact the tire with the lip on the outer fender. No way to change that, whereas too much offset can be corrected with a spacer. Here's a thread I made on making clearance for big rubber.

 

[Robert M]

I have 12" Alcoa's with 325/30's and no mods at all to my car. I did have to remove the rear brake ducts and the Eibach rear shock dust boots, but no cutting or modding on the car itself..........

............and 275's on 10" Alcoa's up front.

I originally installed 335/30 Michelin PS2's on the 12" rears, but it was almost getting to look like a "fat man trying to fit into a speedo", and I was not interested in that look.






R

 

[enormous]

I just received my 2nd set of 325 30 20 Michelin Sport Cup 2 from the Tire Rack at a very good price of $345 ea. My originals cost $550 each.

 

[Robert M]

I just received my 2nd set of 325 30 20 Michelin Sport Cup 2 from the Tire Rack at a very good price of $345 ea. My originals cost $550 each.

^^^Competition does wonders for the marketplace.

Remember when the Dunlop SP Sport Maxx GT's in the 325/30/20 size were $800ea.? $1600 for two rear tires (plus shipping)!!!........<<At that time they were the only manufacturer making them........




R

 

[Pribilof]

I just received my 2nd set of 325 30 20 Michelin Sport Cup 2 from the Tire Rack at a very good price of $345 ea. My originals cost $550 each.

You must have gotten 2 out of the last 3 tires they had. I ended up having a Mercedes dealer order mine from an out of state dealer. $360 each. OEM tires on the SLS Black Edition.

 

[Pribilof]

Got everything mounted today on Forgestar CF10.

275/35R20 MPSS on 20x9.5 +29
325/30R20 MPSC2 on 20x11 +56

I cut out the bumpstop bracket and relocated the bumpstops over the weekend. Not sure if I needed to or not but it was easier to cut them out and not worry about it than to get to Discount Tire and have a clearance issue. I did not cut the shock dust covers. There is still about 0.5" clearance between those and the tires.

 

[ShelbyGT5HUN]

How does the car handle and hook up with such wide tires? Do you notice any negative effects running such wide fronts? Any tracking issues, or loss of agility going side to side?

 

[Catmonkey]

Post up pics. How's the clearance on the outer fender?

 

[Robert M]

How does the car handle and hook up with such wide tires? Do you notice any negative effects running such wide fronts? Any tracking issues, or loss of agility going side to side?

Putting a 275 tire on the front of my heavy nosed 2008 GT500 was one of the best handling upgrades I did to my car. I could feel an immediate difference when pushing the car moderately into a turn, it seems to dig-in and grip and is capable of higher entrance speeds onto ramps on and off the interstate.

I laughed when I first saw a 255 tire on the front of my GT500, 1994/95 Cobra's had 255's and they were 3600lb. cars or less, maybe more like 3500 or 3550!! Heck, a 2003/04 Cobra had 275's on all four corners!! <<I think they were approx. 3640lbs. or so. When the front tires are carrying the load into a turn, a larger front tire can really help, especially as the pork begins to add to the load they need to carry into those turns.

The first time I drove my car with the front tire and wheel width upgrade was to the end of my street, there is a cul-de-sac at the end. That was the first place where I did a few tight circles and found out WOW!!, my car feels pretty good now when doing tight turns (it doesn't feel like it is plowing)!! Then I started experimenting with the higher speed turns and found the much better, more planted feel in turns.





R

 

[Pribilof]

I agree with Robert. The car feels much better with the 275s in front. The sidewalls are the same height now in front and back, which I thinks looks a lot better.

Passenger side rear sticks out maybe 3mm and the driver side roughly 1mm. That's an eyeball measurement.


I'll get some more pictures when I get out of the garage.

 

[Robert M]

^^^An adjustable panhard will fix that.

What I did, since my sidewalls also have a slight bulge past the fenders (not the tread, but just the sidewalls) I first put the back up on jack stands (under the axle) with the suspension compressed, and then adjusted the panhard bar, pulling the body in the direction I needed it to go. I had it on jack stands so that there was no tire bulge from sitting on the floor, and I could lay a straight edge across the full outside tire surface and get an equal measurement between the straight edge and the fender lip.

I think I am out 1/8" exactly on each side, maybe 3/16"? <<<Nothing that is really noticed, unless someone stands over the rear tires and starts to closely examine the rear tire bulge and the rear fender lip.









R

 

[ShelbyGT5HUN]

Robert,

I laughed when I saw the 285 rear tires!

I see what you are talking about with the fronts. I know, and I've only done this at low speeds (40 and under), that the front tires wash-out / understeer heavily, on sharp corners. I never gave much thought that it could be due to the narrow tires. I am going to reconsider my options, as I need new tires now anyway.

 

[Ohio Snake]

I went 305/35/ZR20 on back 20x10.5
And 285/35/ZR20 on the front 20x9.5

I have the Shelby Venice wheels. Hookup and handling much better.


Sent from my iPad using Tapatalk

 

[Pribilof]

If you do the math on some of these widened wheel cobinations, you'll see that they're in the 57-62mm offset range. Less than 57mm and you push the tire further outboard and may contact the tire with the lip on the outer fender. No way to change that, whereas too much offset can be corrected with a spacer. Here's a thread I made on making clearance for big rubber.

Bumping this thread back up due to all the recent tire threads. Also, I fixed my picture links.

Catmonkey is correct on the offset. I have +56mm in the rear. If I was going to do it again I'd probably go with +60mm. I may have the back of the wheels machined to take 4mm off the mounting pad. Or I may just get a 9" rear end and have them shorten the axle tubes so I can run a less extreme offset to begin with.

I still owe everyone some pictures. The car is on stands at the moment but I'll get the pics up eventually. Also considering BMR lowering springs and Strange struts / Viking shocks so you may get to see this combo with a 1.5" drop.