Stuffing 275's into a GTPE (square setup)

[apailthorp]

What about 275s on 18x9 or more likely 275/45R19 on 19"x9"s (ET ~ ?), anyone try for that on a non-PE? Personally I decided I wasn't willing to spend the 6K when I'd probably want to buy my own summer rubber, maybe swap in some aftermarket struts or coil overs, and didn't like the PE seats as well.

But if I do decide to try some summer performance rubber with a nearly three ton car, curious about any other 275 installs people have done. TIA

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[androidphat]

Lots of wheel and tire guys say you can't put 275's into a GTPE, at least on the front. But I did it! I used MRR FS06 20"x9" forged flow formed wheels, with (this is IMPORTANT!) a +35 mm offset, i.e., an ET35 setup. This gave me a finger's clearance on the inside edges of the wheel wells. Why not go with 295's on the rear? Because I'd need a wider wheel on the rears, which would disallow tire rotations (10" wouldn't fit on the front), and most importantly, GTPE's already understeer, so why would I add more? I bought the new adjustable Steeda anti-sway rear bar, to dial out the existing (pre-wheel/tire change) understeer (increases the rear anti-sway from 200 pounds to 250-300-350 pounds).

Why not use forged? I got two bids on fully-forged wheels, with one quoting $1500/wheel, and the other $1250/wheel. Neither would guarantee fit. The MRR's were $590 each, including free shipping! MRR also said that 275's wouldn't fit on a GTPE...which just means that they hadn't gotten word that it would work from an end-user. The forged wheels weighed about 23-24 pounds each...the 9" MRR's weighed 26.2 pounds (I weighed the MRR's myself on a digital scale). That compares to the stock GTPE 8" forged flow-formed wheels at 29.5 pounds.

MRR uses different procedures from other wheel manufacturers. They have the wheels built in Taiwan (like everybody else), but the wheels are shipped in an uncompleted state. The offset, bore, surface treatment and powdercoats haven't been done yet. MRR pre-orders many, MANY of these unfinished wheels, and stores them in Caliifornia. Then, when you order the wheel you want, you get to specify the bore, offset, surface finish and color yourself. They then finish making the wheel in California. Whereas the other two wheel companies specified a 4-6-WEEK wait for the wheels, MRR specified a 6-DAY wait! My wheels, which had an extra custom finish, involving extra labor (and cost), were ordered at 4:30 pm on a Friday, and delivered to me 8 days later, on the next Saturday, at 12:30 pm. Did I mention the shipping was free?

The wheels came with a 66.6 mm hub bore, and the Mach-E's have a 63.4 mm hub. My fault, I didn't specify the hub bore...I would specify a 63.7 mm bore if I did it again. I added 63.4 mm-to-66.6 mm hub ring adapters (plastic), so the lug bolts wouldn't be carrying all of the weight.

I worried about how hard it would be to force 275's onto 9" rims (the wheel specs for these tires say 9"-11" wheels are okay). So I coated the outsides of the wheels (1 coat), including the TOP OUTER EDGE, and the inner surfaces of the barrels (2 coats) with Gyeon Rim Q2 ceramic coat. The Gyeon Rim ceramic is a special high-temp coating, made to withstand the high heat from brake calipers. So far, brake dust doesn't seem to stick. When I finished the coatings, the insides of the rims felt like glass. Note that this is a "Pro" coating ($50 on Amazon), but I had no problem applying it. NOTE: on YouTube, the guys showing you how to apply it are doing it wrong...they're applying it much too heavily (I had NO "high spots" when I did it). Just read (backside of the front label) the directions, and follow them, and watch the application video Gyeon has on their website. I had enough of the rim ceramic "vial" left to maybe do 1 additional coat on 2 more wheels.

My tire guy (Premier Mobile in W. Sacramento...find him on the Tire Rack site) said that he had no problems getting the tires on..."probably due to the ceramic coat". Note that I put NO ceramic on the inside edges of the wheel lips (where the tire rests against the rims).

Finally, I had to do a very slight mod to the inner rear felt fender liners. They hang loose from the inner wheel-well metal, and have about a .5" gap between the felt and the metal. I used a 6" piece of black gaffer tape to pull the felt back to the inner well's metal at one point. If you crank the front wheels to the extreme left or right, you can hear/feel a very slight rubbing on the felt liners, but only from a dead stop (like exiting a parallel parking space). I hear/feel no rubbing while cornering, fronts or rears. And no scraping on the front wheel well lips...no grinding necessary! Gaffer tape is like duct tape, but it's stronger and has a MUCH stronger adhesive. I hung some paintings temporarily on a set wall once, with small loops of gaffer tape, and it pulled the outer-and-middle surface of the drywall off. Sold at motion picture supply stores in Hollywood.

Results? My GTPE corners much harder before slipping. And the car feels MUCH more planted on the road (probably due to both the increase from 245 to 275 in width, and the decrease from 45% to 40% on the aspect ratio). General (owned by Continental, who also owns Hoosier) G-Max RS's came in third in Consumer Report's "High Performance Tire Tests", slightly behind Michelin Pilot Sport 4S's and Pirelli P Zeros. Their wet braking was better than either of the others.

I got the G-Max's for $196 each, when the Pirellis were $348 and the Pilot Sports were $379. AND the G-Max's have a wear rating of 350, which I feel that our heavy cars need. Tire noise is slightly more (5%), and the ride is slightly stiffer (5%). They have a 10.82" tread width. Range? I'm doing a mountain drive from Tahoe to Nevada this weekend, and will report back.

Hello.

I ordered 20X9 +35mm wheels with 275/40/20 square tire for my car 2022 Mach-E but I got email from extremecustoms.com
Said here
Hey Gerson! I did see those tires are a bit wider than your original OEM sizing as well as the wheel is a full inch wider as well. There's a chance you rub at full turn. Will that be okay?
Cameron K.
-Extreme Customs

That true??

 

[RetiredDP]

Hello.

I ordered 20X9 +35mm wheels with 275/40/20 square tire for my car 2022 Mach-E but I got email from extremecustoms.com
Said here
Hey Gerson! I did see those tires are a bit wider than your original OEM sizing as well as the wheel is a full inch wider as well. There's a chance you rub at full turn. Will that be okay?
Cameron K.
-Extreme Customs

That true??

As stated in my arrival, I got a VERY slight rub on the inside felt liner initially. Nothing to worry about. But, as stated, I pushed that felt liner away from the inside of the wheel and tire by taking some gaffer tape (like duct tape, with stronger adhesive), sticking 4 inches worth on the outside of the felt liner, and pulled the liner into firm contact with metal wheel well (and wrapped the rest of the tape around to the backside of the metal wheel well). After doing this mod, the tire will rub slightly on its inner shoulder when you're in FULL LOCK, but no damage is done. I've been driving it this way for 3 years. Just remember to have that -35 mm offset on the wheels. No problems with clearance where the outer edge of the tire meets the outer wheel well lip (no rolling the lip or trimming the lip needed). My GTPE doesn't have any plastic black molding on the fender arches...that's thicker, and might need trimming?

 

[androidphat]

Oh, what about a wheel spacer? What size do I need to get a wheel spacer?

 

[RetiredDP]

Oh, what about a wheel spacer? What size do I need to get a wheel spacer?

Huh? Why would you use a wheel spacer? 20x9 35mm offset wheels with 275/20/40 tires are going to just barely fit...you couldn't possibly space them out any further.

 

[androidphat]

At +35, my tire will going to be poking out from the fender lip molding? If yes then I would be more concerned with the outer sidewall contacting the fender lip molding when going over a dip or large bump in the road.

 

[HuntingPudel]

At +35, my tire will going to be poking out from the fender lip molding? If yes then I would be more concerned with the outer sidewall contacting the fender lip molding when going over a dip or large bump in the road.

Here is the spec on my custom wheels: ??

This is what they look like and how far they are proud of the fenders: ??

Much more negative aftermarket offset will not fit unless the fenders are flared. ??

 

[androidphat]

Look nice!

 

[RetiredDP]

At +35, my tire will going to be poking out from the fender lip molding? If yes then I would be more concerned with the outer sidewall contacting the fender lip molding when going over a dip or large bump in the road.

I've had no issues with ET35, and my tires (General GMax RS's) have quite a square profile.

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