So why don't 10in wide square setups work?

[Boone]

AM also has a coupon code good through 9/30. The code is CLEARANCE10, and it will get you an additional 10% off. I'm thinking of pulling the trigger on some 18x10's ET45 wheels for track use. I'm not ready for them yet, but the price is surely right.

 

[Norm Peterson]

I searched and found several comments saying the GT4 18x10 work on stock 05-09 GT calipers up front without spacers. Before I pull the trigger, has anyone had direct experience with this setup?
AM has the chrome ones on clearance now...$89/ea.

No direct experience, but if the offset is +42 or a little less the wheels will fit. Tire size might be limited, however.



I have about 10mm strut side clearance with 18x9.5 ET+45 GT500 wheels. You'd lose 6.5mm off of that by going to 10's, but gain 3mm back with ET+42. I could plot up a comparison if you provide the GT4 offset and a tire make, model, & size.


Norm

 

[dark steed]

No direct experience, but if the offset is +42 or a little less the wheels will fit. Tire size might be limited, however.



I have about 10mm strut side clearance with 18x9.5 ET+45 GT500 wheels. You'd lose 6.5mm off of that by going to 10's, but gain 3mm back with ET+42. I could plot up a comparison if you provide the GT4 offset and a tire make, model, & size.


Norm

Their website lists offset as +45. So that will hurt me on the clearance?
Thinking of the NT555 again in 275/40-18, I had them in 255 on my 18x9's.
Currently running Conti DW, but they barely lasted a year

 

[Norm Peterson]

Based on what room I have with Koni yellow struts and my wheels and tires, I see your wheel having 1/8" or slightly more clearance to the strut. But that tire may well need a thin spacer (and most probably longer lugs) as it bellies out about 3/16" more past a 10" wheel more than my GY tire does past a 9.5". Struts other than Koni yellows may offer more or less clearance, so you may or may not have any wiggle room here that I haven't tried to account for.

I have about 10mm, maybe 0.40" strut side clearance, tire and wheel, for the picture below, yours being the red trace. If it's too close to call, you could try measuring your clearances and I could work up a comparison to those. Strut side is to the left in all three views.

Norm

 

[dark steed]

Thanks. I test fit it today and have about 1/4" clearance between the rim and the strut.
I am very new to this and am uncertain if this would need a spacer. The rim is about flush with the fender.

 

[NUTCASE]

Just saw this

High five for another one with the GT4s. I have black with polished lip 18x9 and 18x10

I think they look awesome and are lighter than GT500s along with a lot of other wheels. I forget exactly what they weigh but they are something like 24 or 26#. Eventually I want to throw the rear ones on the front just to see what the fitment looks like and if I can get two more 18x10s

I have no idea why these wheels were never popular. Everyone that sees my wheels loves them.

 

[NUTCASE]

Some pics of mine

 

[Norm Peterson]

Thanks. I test fit it today and have about 1/4" clearance between the rim and the strut.
I am very new to this and am uncertain if this would need a spacer. The rim is about flush with the fender.

1/4" is a ton of room at the wheel. If it ever flexes that far you've got a much bigger problem to solve.

At the tire, the 275/40 sidewall bulges out about 5/16" past the wheel, which would be more than your 1/4" clearance except that the strut angles inward as it goes up, and that should gain you at least another 1/4". Leaving you with about 3/16" tire clearance, which should be plenty.


Norm

 

[dark steed]

Just saw this

High five for another one with the GT4s. I have black with polished lip 18x9 and 18x10

I think they look awesome and are lighter than GT500s along with a lot of other wheels. I forget exactly what they weigh but they are something like 24 or 26#. Eventually I want to throw the rear ones on the front just to see what the fitment looks like and if I can get two more 18x10s

I have no idea why these wheels were never popular. Everyone that sees my wheels loves them.

I think they will look good on the black car. I currently have the FR500 18x9 black/polished lip. Just wanted to to change things up and these were on clearance.
Those look great on your car!

1/4" is a ton of room at the wheel. If it ever flexes that far you've got a much bigger problem to solve.

At the tire, the 275/40 sidewall bulges out about 5/16" past the wheel, which would be more than your 1/4" clearance except that the strut angles inward as it goes up, and that should gain you at least another 1/4". Leaving you with about 3/16" tire clearance, which should be plenty.


Norm

Thanks, I figured if to flexed that much I'd be in trouble. I can fit (barely) my pinkie between the rim and strut.
Speaking of the tires, this will limit tire width, I'm sure. I'm currently looking at the NT555 in 275 ($174 ea at Discount) and the Bridgestones Potenza RE760 Sport. A buddy works at Bridgestone and is checking on his discount.
Do you (or anyone else) have experience with these? Do they run wide or narrow for the size?
Rick

 

[Norm Peterson]

Thanks, I figured if to flexed that much I'd be in trouble. I can fit (barely) my pinkie between the rim and strut.
Speaking of the tires, this will limit tire width, I'm sure. I'm currently looking at the NT555 in 275 ($174 ea at Discount) and the Bridgestones Potenza RE760 Sport. A buddy works at Bridgestone and is checking on his discount.
Do you (or anyone else) have experience with these? Do they run wide or narrow for the size?
Rick

The dimensions and clearances posted are based on Nitto's actual section width measurements. I haven't checked the B'Stones.


Barely fit a pinkie?

Try 'barely fit a credit card, and only as long as you don't try to squeeze the embossed lettering' into the clearance space. It does not rub, even at a track day.

Norm

 

[dark steed]

Wow!! That's tight. I have Koni oranges to put on it too, and LCAs, and relo brackets, and Hot Rods, and...
I need to take a week off and just do car stuff!
Speaking of the Koni's, are they the same diameter as the stock (GT500 take offs)?

 

[Norm Peterson]

Speaking of the Koni's, are they the same diameter as the stock (GT500 take offs)?

I don't know, nor do I know if the distance from the centerline of the strut axis to the bolt hole centers is the same as stock. It never occurred to me to make these measurements when I installed my yellows (this being back when I was only looking at installing 255/45's on 18x9.5 GT500 wheels).


Norm

 

[redline8k]

Anyone have a pic of 18x10 amr gt500 reps on all four corrners? I really want to see how the front wheels look. Im thinking 275s in front and 295-305 in back.

 

[SlowJim]

Don't go wider than 285 on a 10" rim. Even that is pushing it. Mods can we make this a sticky?

http://www.motoiq.com/MagazineArtic...LY-select-and-size-TIRES-for-PERFORMANCE.aspx

 

[Boaisy]

I had 295's on mine...

 

[Mach2burnout]

Don't go wider than 285 on a 10" rim. Even that is pushing it. Mods can we make this a sticky?

http://www.motoiq.com/MagazineArtic...LY-select-and-size-TIRES-for-PERFORMANCE.aspx

I will argue that all day long. I guess you believe that a 275/45 fits properly on a 10" wheel.


Sent from iPhone

 

[Norm Peterson]

I will argue that all day long. I guess you believe that a 275/45 fits properly on a 10" wheel.

Actually, 10" is a very good width for 275-wide tires in 45 or lower profile. 275/xx is mfr and Tire & Rim Association approved for wheel widths out to 10.5", so 10" really isn't all that extreme. Hell, Ford and Chevy both have used max wheel width fitments in regular production - 2008 Mustang GT (235/50 on 18x8.5), 2008 GT500 front (255/45 on 18x9.5), and the 1LE Camaro rear (285/35 on 20x11).

What you see in SCCA Stock/Street category autocrossing (wheel width limited, tire size not) provides a distorted picture of what constitutes proper fitments. It may be the best you can do when you're stuck having to operate under that ruleset, but that doesn't make it optimum anywhere else. The only reason some of the autocross fitments I've seen or read about "work" is because of the extreme shortness of each run and the guaranteed cool-down time in between that keeps the carcass from overheating.

"Measuring width" fitments are at best a middle-of-the-road compromise between ride quality and qualities such as steering precision.


Norm

 

[Pentalab]

I will argue that all day long. I guess you believe that a 275/45 fits properly on a 10" wheel.


Sent from iPhone

Dunno about a 275-45.... but a 275-40 makes a perfect fit on a 10" rim. From my limited experimentation, it appears that using a rim that is 1/2" wider than the... 'measuring width' provides optimum performance. But some tire makes are wider or narrower for the same '275' etc, vs different tire manufacturers.

I started off with 275-40-18's on 10" wide rears..and also 255-45-18's on 9" fronts. Then swapped the rear 275's for 285-40-18's. (same 10" rim). After some tweaking of rear tire pressures, they appear to function slightly better.

The fronts are a different story. A year later, I swapped the front 255's for the 275's (that were in storage). Both on 9" rims. I'm not really impressed. Although the min width for a 275 is 9", I feel it's not optimal. Feels sluggish on corners with initial turn in, but sticks ok.

I may well swap the 255's back onto the front 9" rims next spring..(or use new 10" rims on the front..with 275's, or perhaps 285's).

Looks like for every 1/2" change in rim width (wider / narrower) the tire is 5mm ( .2") wider /narrower. I should have listened to Norm the 1st time round....a yr ago.

The older GT-500's used 255-45-18" on a 9.5" rim.... which imo, is too wide. They appear too stretched for my liking. They also used the same 9.5" rim for the rear ( both had the same et)..with a 285 tire. IMO, a 9.5" rim is too narrow for a 285 tire.

 

[Norm Peterson]

The older GT-500's used 255-45-18" on a 9.5" rim.... which imo, is too wide. They appear too stretched for my liking.

Right about here is where you either appreciate a mildly stretched appearance because you understand what it's giving you (which is a little like inside information) . . . or you can't come to terms with it because it's "too different" from the gently half-rounded shape that tire sidewalls have traditionally looked like.


My guess for what Ford did with the GT500 tire sizes was to pick sizes that would both legitimately work on the same rim. Min width tire at one end, max width tire at the other. Simplifies inventory and saves production cost. I did hear somewhere that Ford actually wanted to run 'square' tire sizing on the 5.4L GT500, but couldn't fit the handling inside corporate standards.


Norm

 

[Mach2burnout]

Just because manufacturers say it'll fit don't make it optimum. In my experience 275 tires are too narrow for 10" wheels. They fit optimally on 9.5" wheels. He'll manufactures say a 305 is a good fit for a10"-12" wheel. Optimal being a 11" iirc. My point was a 285s work well on a 9.5 - 10" wheel. A 295 will as well. His comment was "do not go wider than 285 on a 10" wheel" I just called BS on that.


Sent from iPhone