275 45/R18 Square Setup On S550?

[DesertRat5115]

I'm getting ready to get some decent rubber on my month-old car (stock 2019 GT - non-PP) and considering options, looking for thoughts.

I'm currently still running the stock 235 50/R18's and am considering 275 45/R18 on 9" wheels, square setup. I understand that this size should work up front, just not sure what the offset should be yet so that there is no rubbing, and I'm just starting to investigate. The roads here really suck and I want as much sidewall as is reasonable, so I'm happy to stick with 18" wheels. I know that cornering might not be quite as sharp as 19's with a lower aspect ratio, but then again smaller wheels offer a weight advantage (at similar price point), and I want the cushion anyway. So a few questions:

Anyone running this setup and if so how's it working out?
I know that I can find 275 45/R18 tires that are approved to work on 9" wheels (even 8.5"), but am I missing a significant part of the gain in tread width by not using a wider wheel? If so, thoughts on running a wheel wider than 9" on all four wheels? I'm thinking it would begin to look strange up front?
If I were to run the 275 45/R18s on 9" wheels all around, what would the correct offset range if anyone knows?
This overall diameter would be +1.5% with this size. A few people have suggested going 275 40/R18. There I would be -2.2% smaller and I would be losing some sidewall which I'm trying to keep. Also at stock height, I feel the wheel wells already look too empty, so I don't really want to go with a smaller overall diameter, and I don't mind riding a tiny amount higher with those 275 45/R18s. Also I know that the 45 aspect ratio tire is better suited to a 9" wheel than the 40 aspect ratio tire is. However, it seems the 40 aspect ratio tires are a lot less expensive, so is anyone running 275 40/R18 on a stock height S550 and if so how's that looking / working out?
Overall is it better to just buy new TPMS and sell the old wheels / tires intact to possibly sell? Any issues with aftermarket sensors to watch out for?
Recommendations on the best places to shop?

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[PanicSwitch89]

Not sure I can answer your question perfectly, but I went 275/40R18 (BFG G-Force Comp 2 A/S) all four corners with SVE S350 Wheels:

Size: 19x10
Backspace: 7"
Offset: +40mm
Weight: 24lbs


I drive on a lot of crap roads and hit a lot pot holes in Maryland, no problems whatsoever.
It should be here on the forum somewhere as far as the stock diameter, and you can google a calculator if you want to match it. All depends on the tire too (contact patch, section width, etc.)

For TPMS sensors search this on Amazon, make sure it says made by Ford. Other sites like LMR and American Muscle want way too much.
TPMS35 F2GZ-1A189-A (4) Tire Pressure Sensors 2015-17 Ford F-150 Edge Mustang

 

[DesertRat5115]

Thanks, and it seems 10" is the common wheel width for that tire.

I'm probably in a small minority but prefer a bit of sidewall bulge and the wheels I really like (Konig Oversteer) only come in 18x8 and 18X9, so I'm somewhat committed to that 9" width. A positive is that this 18x9 wheel weighs only 20 pounds, not bad for a modestly priced wheel. It also has a unique look.

It sounds like the tire size will fit for sure, it's just a matter of hopefully finding out what the offset would need to be so that there is no rubbing...just not sure where to find that information.

 

[PanicSwitch89]

Hopefully someone chimes in that knows more, I'm no expert. Did you look at https://tiresize.com/wheel-offset-calculator/

Might give an idea. If you take anything from this, order the Tpm's sensors on amazon.

 

[DesertRat5115]

Hopefully someone chimes in that knows more, I'm no expert. Did you look at https://tiresize.com/wheel-offset-calculator/

Might give an idea. If you take anything from this, order the Tpm's sensors on amazon.

Yes, I used that calculator to determine that my diameter will be reduced by 2.2% with the my new 40 series tires when compared to the stock 235s, it's a great tool.

I dug a bit more this afternoon and visited my nearby discount tire who happens to sell the wheel I want. They informed me that they have installed that wheel and tire size on S550 Mustangs multiple times without any issues, and that the recommended offset is 22 with that combination.

Everything is now ordered including those OEM TPMS units you suggested on Amazon, $50 for four of them. Can't wait to get everything installed, 235s just look and seem so "wrong" on this car, especially when you look around and see that even the most lowly Camaro or Challenger has wider tires than that. Not a big deal though, I get that Ford put their dollars into the drive-train on this car, and that having bigger tires = extra money whether as a factory option or purchased afterwards.

 

[PanicSwitch89]

Nice, I'm sure it'll look great. Clearly your next step after wheels is twin turbos of course.

 

[USMCtoARMY]

Well I'm late to this conversation but 45 series tires will look truckish or ole school. 40s height look best and that 22 offset will not properly fit. 1994-2004 ran those offsets. I recommend to spend more time here in the wheels and tires thread. I ran 18×9 as my first set of rims for this car at a 35 offset. The were a set it had on my previous Mustang and holdover set till I could upgrade. I went 19×10 later and I can tell you the car handles (more stable, sticks) and feels a lot better than before The consensus tire package for our cars are 19×10 with 275 40 or 285 30/35 in and around a 32-36 offset (wheel dependent). I would check out this link:

https://www.oewheelsllc.com/make/Ford/model/Mustang/year/2016

If you want a PP rim that is cheaper, durable, factory looks, in the proper offset, and in 18 or 19. Otherwise, wait for a sale on LMR or MRR.

 

[OlTexastang]

I had 265/45/18 et 20 on my Eco and they fit with no rubbing car was not lowered and camber was at stock, 22 offset should be fine.

 

[USMCtoARMY]

Those look short for 45s....must be Michelin. I would have to see a 22 offset fit in 18s. A guy a loooong time ago put 22 offset bullit rims on his car and the poke was unreal (maybe I'm off on the offset, not sure).

 

[Grintch]

Yeah +22 sounds like it will poke in the rear to me.

 

[OlTexastang]

They are Michelin’s but like I said 20 offset not lowered it looked like it would rub but never did. There was some poke but with the 4x4 wheel well clearance it was ok.

 

[DesertRat5115]

Great pictures, and input, thanks. Your car looks very nice OlTexastang, as does your wheel / tire package. I know that some might say that 245/45's might have a bit too much of a fat-tire look, but I prefer more sidewall for the "war zone" type roads I have to drive over. If I had really nice streets to drive one, I might even consider 19's or 20's. Shorter sidewalls look nice, no argument. But it's not for my daily commute.

*So an update. After ordering the first wheels I wanted, I got an email letting me know that the wheels I wanted would not fit correctly, that the first person was mistaken. The second guy seemed to know quite a bit more and had the right information on what wheels would and would not fit the car, and why. He mentioned that a big issue for some wheels on this car is caliper clearance, even with standard brakes (problem with my first choice). At he explained things, offset is largely a function of wheel / spoke design, and it varies. He did mention that even though the Konig wheels would not work because of caliper clearance, the offset quoted was way off regardless, and needed to be a higher number, 35-40 for most wheels that are 9 - 9.5" wide.

Anyway, we found a wheel that I liked, and that he said should work well, a TSW 18X9.5, with an offset of 40, 24 pounds, so we got them ordered, and they should arrive tomorrow or Wednesday. I will be mounting 275/40/R18's on them Friday or Saturday when the tires arrive. I went down on aspect ratio because I got a really good deal on 40 series rubber and figured "why not"? Also, there is generally a more affordable selection of 40 series than 45 series in 275/R18, but the jury is still out for now on my end. I'm going to burn through this set and decide whether I want to stick with 40 series or go to 45 series.

If I want to go to 45 series later, or even if I stay with 40 series, I'll get Michelin rubber. Although I agree that a 10" wheel might be ideal, I think that the 9.5 should work out for me as I like a tiny bit of sidewall pudge (I guess I'm old school that way).

I'm really curious to see how much of a tramlining issue I have with fronts this wide. Can't wait.

 

[OlTexastang]

Great pictures, and input, thanks. Your car looks very nice OlTexastang, as does your wheel / tire package. I know that some might say that 245/45's might have a bit too much of a fat-tire look, but I prefer more sidewall for the "war zone" type roads I have to drive over. If I had really nice streets to drive one, I might even consider 19's or 20's. Shorter sidewalls look nice, no argument. But it's not for my daily commute.

*So an update. After ordering the first wheels I wanted, I got an email letting me know that the wheels I wanted would not fit correctly, that the first person was mistaken. The second guy seemed to know quite a bit more and had the right information on what wheels would and would not fit the car, and why. He mentioned that a big issue for some wheels on this car is caliper clearance, even with standard brakes (problem with my first choice). At he explained things, offset is largely a function of wheel / spoke design, and it varies. He did mention that even though the Konig wheels would not work because of caliper clearance, the offset quoted was way off regardless, and needed to be a higher number, 35-40 for most wheels that are 9 - 9.5" wide.

Anyway, we found a wheel that I liked, and that he said should work well, a TSW 18X9.5, with an offset of 40, 24 pounds, so we got them ordered, and they should arrive tomorrow or Wednesday. I will be mounting 275/40/R18's on them Friday or Saturday when the tires arrive. I went down on aspect ratio because I got a really good deal on 40 series rubber and figured "why not"? Also, there is generally a more affordable selection of 40 series than 45 series in 275/R18, but the jury is still out for now on my end. I'm going to burn through this set and decide whether I want to stick with 40 series or go to 45 series.

If I want to go to 45 series later, or even if I stay with 40 series, I'll get Michelin rubber. Although I agree that a 10" wheel might be ideal, I think that the 9.5 should work out for me as I like a tiny bit of sidewall pudge (I guess I'm old school that way).

I'm really curious to see how much of a tramlining issue I have with fronts this wide. Can't wait.

Thanks, I put those on because the wife was driving it and didn’t like how the 265x35x20 Pirelli’s rode, she has since moved on to another vehicle so I put 285x35x19 Conti Super Sports on and it (10” rims) still has a much better ride than the Pirelli’s. Hope you enjoy your new rims.

 

[DesertRat5115]

I got the 275/40R18-9.5" square setup on today and wanted to share what it looks like. Finally, some respectable-width tires on a 460 HP car. I mean, I love the car, but 235's stock?

Anyway...the overall change in appearance was surprisingly un-dramatic, as you can see in the attached picture (except from a low front / rear view, where you see the dramatic difference in width). I don't have a rear before pic, but those skinny tires were pretty sad looking especially from behind, and most know what I mean.

Overall I was lowered about .4 inches, but it's not really noticeable for me, and a 2.2 MPH speedometer difference at 100 MPH, who cares? The TSW Crowthorne wheels (offset 40) were light for the price-point and do the job, no regrets there. I personally like the low-key look of these wheels in matte black. They poke out a tiny bit more to fill the wheel wells, but look perfect to me. The casual observer wouldn't even notice the difference. My overall gearing has now improved a tiny bit for launches as well, not much, but I'll take it (slightly smaller overall diameter). As a matter of fact, I think this would be a perfect stock square fitment, it's that sweet. Those wheel-wells are WAY too wide for 235s.

I went with low price tires, Federal SS595s, and wasn't expecting anything amazing. But the grip, and road noise, are more than good. There is zero tram-lining. So don't let anyone tell you that putting 275s on the front will cause some big issue. Maybe with some tires, but not these. The grip is probably twice what the stock tires had in a straight line or in a hard corners. Having a wider tire and wheel does wonders over potholes too, because it's less likely that you will sink a wider tire in a pothole. I noticed that immediately. In fairness, reviewers state that you need to be careful when it's wet, they don't have a lot of tread. And I will be keeping that in mind when it rains. I'll burn them up and probably get Michelins, but I got a great deal and saw good reviews and thought I would shake them out...a spontaneous idea that seems to be working out so far.

Bottom line, I could have probably gone with 285s, but I'm very happy. Now I just need to break out a bottle of tire shine and get them looking respectable.

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