Why no spare option for 20's?

[Old 5 Oh]

Well or the Brembos ;)

The question was "why not on cars with 20s?" NONE of the Brembo cars have 20s. That's PP only, and they have their bespoke 19s. Period. No options.

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[embraceentropy]

So, the consensus is to get the factory spare and install a 135/80R18 or 145/80R18 tire on the factory spare rim. It should fit, but if not, then deflate the tire.

Does anyone have any operational experience with this?

 

[byklin]

Whether you have the base 235/55-17, 235/50-18, 255/40-19 or 265/35-20 they all have the same outside diameter of 27.3" only the GT PP rear 275/40-19 is larger at 27.7"

The optional spare tire is available all versions except those with summer tires, you can get it with the Aniversery package which has 255/40-19 all season tires.

I can understand the GT PP because the wheel won't fit over the PP brakes but it will clear the brakes on all other versions so it's not an outside diameter thing. The digging I have done the spare has a 185/55-18 tire.

This is correct. Most OEMs measure 27.3" so technically the spare will work with any size with an OD close to 27.3". If your aftermarket wheels have a 27.3" OD, you should still be able to use the spare.

 

[dgc333]

So, the consensus is to get the factory spare and install a 135/80R18 or 145/80R18 tire on the factory spare rim. It should fit, but if not, then deflate the tire.

Does anyone have any operational experience with this?

The factory spare is a 185/55-18, no need to change the tire. Ebay has multiple sellers offering the factory kit which includes the spare, jack, wrench and hold down hardware for low to mid $200's.

 

[Blk2015GT]

The factory spare is a 185/55-18, no need to change the tire. Ebay has multiple sellers offering the factory kit which includes the spare, jack, wrench and hold down hardware for low to mid $200's.

Actually it's 155/60R18 on the 2015 version.

 

[kcphoto21]

Has anyone tried to use a stock spare wheel on the car with 20" wheel/tire package? There must be a really good reason why Ford is not offering that option.

All I am looking for is to get an option to be able to drive 10-100 miles to get to the nearest place that can fix my flat tire. I am sure everyone has driven through a remote place with no cellphone coverage -- in the middle of the night on a weekend.

Many thanks.

 

[embraceentropy]

I received my factory spare tire kit this afternoon.

There was some confusion on the size of the spare in previous posts, so to clear it up, the spare tire is a 155/60R18 (25.3" OD).

Just for documentation purposes, the factory (non-PP) 20" rim option comes stock with 265/35ZR20 (27.3" OD) tires.

That is a 2" OD difference, which translates to 1" ride height difference between the two. The speed difference at 50mph would be 3.7mph between the spare and the other, main tires.

If you upgrade the spare to a 135/80R18, as Blk2015GT suggested, you have a 26.5" OD, which translates to an OD difference of 0.8", or 0.4" of ride height difference. In this case, the speed difference at 50mph would be 1.5mph between the spare and the other, main tires.

So, to discuss the necessity of upgrading the spare tire size. Will 1" of ride height difference and 3.7mph difference (at 50mph) have a negative effect on the LSD, when placed on the rear, or the front suspension?

The question of "will the upgraded spare tire fit in the well" is too close to call for me, officially, without seeing this arrangement in person. It *looks* like it would fit, but it may be tight in the radius in the bottom of the well. Has anyone tried this yet?

For me, this will be a means to get me off the side of the road for a minimum amount of driving, and only if the main tire is not repairable roadside.

Personally, I would be glad to upgrade the tire to a 135/80R18 for peace of mind, but I don't want to waste money for the tire if it did not fit in the spare tire well.

Thoughts? Experiences?

 

[kcphoto21]

Here is the math -- stock 20" vs 18" wheel and tire:

Overall diameter:
(265*.35*2)/25.4 inch + 20 inch = 27.303 inches
(235*.5*2)/25.4 inch + 18 inch = 27.251 inches

I bought the 2015 Mustang with 20" wheels. I saw someone selling stock 18"wheels with stock tires for $200 on eBay. Either that or just buying a standard spare. Question is which one will be better?

Any suggestions? All I am looking to do is to be able to drive ~10-50 miles to get to a tire shop if need be.

Many thanks.

 

[Old 5 Oh]

Any suggestions? All I am looking to do is to be able to drive ~10-50 miles to get to a tire shop if need be.

Many thanks.

Your math is correct, in fact all the wheel/tire packages have virtually the same overall diameter. And since you have factory 20s, you are not a GT-PP and don't have Brembos, so that's not an issue.

The factory spare WILL fit, no problem. The cars Ford does not offer with the spare are all equipped with summer tires. They are apparently worried about handling issues with 3 summers and a temp spare. I am sure that if you mounted a temp spare and tried to set a new PB down your favorite twisty road, bad things would happen. But if you know the potential and drive as though your goal is to make it safely to the tire shop, it should be fine. I have had Mustangs in the past (Foxes and New Edges) with summer tires and temp spares. Seemed to work fine. I really don't know why Ford is hesitant, but it's sure not that the tire won't fit.

 

[embraceentropy]

Good to know. I ran the math in my earlier post on the differences between the factory spare and the 20's (ride height, speed) with the question of whether or not I should upgrade the factory spare to a larger tire. Now, seeing that that OD difference between the factory 18's & 20's is negligible, this will save me some money to blow on other mods!

 

[Strokerswild]

I've posted it elsewhere, but here's why I'll never run without a spare again....

Nothing sucks more than being stranded out in the middle of nowhere late on a hot Sunday afternoon for several hours because a car didn't have a f*cking spare. And no plug or can of fix-a-flat is going to do much here.

 

[embraceentropy]

^This is why I want to figure this out so badly...

Many people have told me that I am off my rocker for being so adamant on this topic (even at the dealership). Ridding yourself of emergency options is never a good idea. In fact, I keep a thorough emergency kit in all of my vehicles. I may put together a post about those kits later.

 

[Jon|3.7]

So what kind of spare tire to I need for 20x10 rims on 275/35 tires......help ): v6 so no brake issues here...

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