Hub centric spacers versus wider tires

[ShadowCoyote]

Ok I have the 19” black accent stock wheels on my 2022 GT and saw that you could get spacers for the rear to have it sit flush in the back, but not to use spacers larger than the thin 8mm for the front. I don’t want to risk suspension geometry so my question is are the spacers a bad idea and if so, what size tires will make the rear and front flush for my 19 x 8.5” stock wheels? Thanks for all your input.

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[NightmareMoon]

There are different types of spacers.

Basic spacers (a disc of aluminum with holes in them) which can be used up to 5mm. I wouldn't go to 7 or 8mm (see thread engagement below... but 5mm seems fine). Even these should be 'hubcentric', but they're too thin to provide their own centering ring, but they're thin enough where the wheel can still grab a bit of the stock centering ring on the rotor. Anything too wide and it gets dangerous fast, as your lug nut can't get enough purchase on the threads of the stud (unless you run aftermarket longer studs).

Thing is, you need 20-25 mm of spacer to get the stock wheels to be flush, and a 5mm spacer isn't much help. (is a little help tho).

Then we have slip on spacers (usually >10mm up to ~25mm with common aftermarket ARP 1" longer extended studs), where they can have a centering ring built in, but are still basically a cylinder of aluminum. To run these you need to replace your stock studs with extended length studs. With this setup you still just have one set of 5x studs and a lug nuts, but now there is a solid piece of billet aluminum between your wheel and rotor hat. They're secure enough to track on, you have full thread engagement if you run proper longer studs, and there are no hidden bits that need checking. If you have a stud which is too long for the spacer you're running, you may need to switch to open ended lug nuts. These cost a little more than the cheaper option below, (really only because you have to buy a set of longer studs in addition to the spacer).

Next type are the questionable ones - bolt on spacers. These bolt onto your stock studs and then have an additional set of lugs which your wheels bolt onto. They're often questionable quality in the metals they use, and now you have 10 studs and 10 lugs per wheel, only 5 can be easily checked w/o removing the wheel. These are the ones we commonly see failures with because those extra studs may not be torqued right, or may be lower quality steel than the stock studs.. or if your wheels don't have pockets big enough, you can have the wheel mounted where it seems secure, but there's actually a gap between the spacer and the wheel. This is the cheapest option for getting stock wheels to be flush.

Lots of people run the questionable kind and get away with it, but its no fun to loose a wheel while driving. I've seen it happen and the sound of the subframe and rotor scraping across pavement while a lone wheel rolls off into the sunset is a cringeworthy thing to witness.

Your other (and probably better) option is to take the $~300 you'd spend on 4x spacers, and save up for a new set of wheels that come with the right flush offsets to begin with.

No amount of tire will fit on your stock wheels and get them to flush. Half because of where the wheel sits in the first place, and half because even if you do squeeze on the widest tire you can fit on the wheel, you still loose about 1/2 the width you'd like to get because its squeezed on a wheel that's too narrow and the tire deforms to match.

 

[ShadowCoyote]

There are different types of spacers.

Basic spacers (a disc of aluminum with holes in them) which can be used up to 5mm. I wouldn't go to 7 or 8mm (see thread engagement below... but 5mm seems fine). Even these should be 'hubcentric', but they're too thin to provide their own centering ring, but they're thin enough where the wheel can still grab a bit of the stock centering ring on the rotor. Anything too wide and it gets dangerous fast, as your lug nut can't get enough purchase on the threads of the stud (unless you run aftermarket longer studs).

Thing is, you need 20-25 mm of spacer to get the stock wheels to be flush, and a 5mm spacer isn't much help. (is a little help tho).

Then we have slip on spacers (usually >10mm up to ~25mm with common aftermarket ARP 1" longer extended studs), where they can have a centering ring built in, but are still basically a cylinder of aluminum. To run these you need to replace your stock studs with extended length studs. With this setup you still just have one set of 5x studs and a lug nuts, but now there is a solid piece of billet aluminum between your wheel and rotor hat. They're secure enough to track on, you have full thread engagement if you run proper longer studs, and there are no hidden bits that need checking. If you have a stud which is too long for the spacer you're running, you may need to switch to open ended lug nuts. These cost a little more than the cheaper option below, (really only because you have to buy a set of longer studs in addition to the spacer).

Next type are the questionable ones - bolt on spacers. These bolt onto your stock studs and then have an additional set of lugs which your wheels bolt onto. They're often questionable quality in the metals they use, and now you have 10 studs and 10 lugs per wheel, only 5 can be easily checked w/o removing the wheel. These are the ones we commonly see failures with because those extra studs may not be torqued right, or may be lower quality steel than the stock studs.. or if your wheels don't have pockets big enough, you can have the wheel mounted where it seems secure, but there's actually a gap between the spacer and the wheel. This is the cheapest option for getting stock wheels to be flush.

Lots of people run the questionable kind and get away with it, but its no fun to loose a wheel while driving. I've seen it happen and the sound of the subframe and rotor scraping across pavement while a lone wheel rolls off into the sunset is a cringeworthy thing to witness.

Your other (and probably better) option is to take the $~300 you'd spend on 4x spacers, and save up for a new set of wheels that come with the right flush offsets to begin with.

No amount of tire will fit on your stock wheels and get them to flush. Half because of where the wheel sits in the first place, and half because even if you do squeeze on the widest tire you can fit on the wheel, you still loose about 1/2 the width you'd like to get because its squeezed on a wheel that's too narrow and the tire deforms to match.

Thank you for the detailed analysis. I really like my stock wheels and it’s a shame they are so skinny. I guess I will just save for a good Wheel and tire package. Thanks again.

 

[glockholiday]

On my 2019 GT/CS it has 19x8.5 wheels with stock size 255/40/19 tires and hate how they're tucked under the fender wells by about and inch. Installed these on all 4 wheels at least 6 months and thousands of miles ago and they're great. Wheels/tires are now perfectly even with the fender wells. No rubbing or change in driving characteristics at all. https://www.cjponyparts.com/accelat...f-4-mustang-v6-ecoboost-gt-2015-2022/p/WAK12/

 

[glockholiday]

Oh but they won't work if you have Magnaride suspension

 

[djcodeman]

You can get a full set of PP1 replicas for under $1000 that are 19x10 and 19x11 , plenty of meat to run wider tires...

https://www.mustang6g.com/forums/threads/19x11-and-19x10-“replica”-pp1.171078/


https://www.beefcakeracing.com/mrr-dg38-19x11gm/

 

[ShadowCoyote]

On my 2019 GT/CS it has 19x8.5 wheels with stock size 255/40/19 tires and hate how they're tucked under the fender wells by about and inch. Installed these on all 4 wheels at least 6 months and thousands of miles ago and they're great. Wheels/tires are now perfectly even with the fender wells. No rubbing or change in driving characteristics at all. https://www.cjponyparts.com/accelat...f-4-mustang-v6-ecoboost-gt-2015-2022/p/WAK12/

I was thinking of doing that but then read that they do not recommend you putting any more than 8mm spacers on the front due to the suspension geometry and it can wear out the front faster.

 

[ShadowCoyote]

A little update on this thread. Does anyone know the offset to run 305 tires on a 18X10” wheel and a 19X10” on a square setup without any modifications or if it is even possible?

 

[rxryanm]

285 is the max tire you should run on a 10 wide. +30-40 is the correct offset for it to be square.

 

[ShadowCoyote]

285 is the max tire you should run on a 10 wide. +30-40 is the correct offset for it to be square.

Ok so if I run a 285X10 with 18” wheels all the way around, is there a specific offset I should use for it to clear everything and be somewhat near flush? How tall should the tire sidewall be to fill in the gap, 40, 45, 50 sidewall? Sorry for all the questions but I am a total rookie when it comes to wheel and tire setups in the Mustang. I want the car to be planted around corners and avoid wheel spin as much as I can without making any modifications to the setup.

 

[cerbomark]

take a look at LMR website. They have light/strong wheels at a good price and answer all your fitment question. Many here have went that way.

IMO, go 19x10 all the way around. more than enough .

 

[MrMike]

19x10 square is super common and will get you the look you're after with better performance from the wider tire. Spacers are a band-aid at best. Run 285/35R19 or 275/40R19.

Apex's fitment guide has some good info:

https://support.apexraceparts.com/h...5483093-S550-Mustang-Wheel-Tire-Fitment-Guide

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