Wheel spacer vs Wheel offset

[Xavierviana]

Whats the difference between wheel spacer (hubcentric) 25mm and a aftermarket wheel with a offset of 25mm less than stock?

(Same wheel width for both option)

For example;

1. Risk for premature failure of the wheelbearing is the same for both options?
2. Suspension feel?
3. Handling?
4. Scrub radius?


Any comment or advise will be appreciated...


Thanks.


Xavier V

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[Brazos609]

A spacer is something that you use to make something work that doesn't work as is. I won't use spacers, I'll just use parts that work as is.

 

[69mach1-395]

Good questions. Of course the optimal solution is not to use them but the difference may not be that significant?

 

[Xavierviana]

Good questions. Of course the optimal solution is not to use them but the difference may not be that significant?

Yes of course since wheel spacer/adapter are two seperate pieces (wheel itself and the spacer) is not recommended for safety purposes.

But about handling, suspension, wheel bearing, scrub radius?

Technically/Theoretically, I think the difference is minimum?

 

[Apex Wheels]

Wheel spacers are used for different purposes, some good and some bad. The general public has a fear of spacers and I'm not sure why, perhaps it's because they are not educated on their uses.

For Mustangs, we have an 11" wide wheel that has an offset of +52mm. We are also coming out with an 11" wide wheel that has an offset of +26mm. Why both? For starters, you cannot easily rotate your tires if you want to run an 11" square setup on the car, as the offsets are much different up front when compared to the rear. This leaves you with the option of having to dismount the tire from the wheel which is costly and time-consuming. If you run the same offset front and back with a spacer in the front, tire rotations are a breeze.

What exactly is it about spacers that are scary? Some have seen studs fail with spacers on them, but without analyzing the stud it's impossible to say that the spacer caused the failure. Unless the stud fracture occurred where the spacer meets the back of the wheel, the failure is not the fault of the spacer. Wheel bearings will not wear any different than a wheel with more offset built in. 11" wheels and subsequent tires generate a lot of grip, which leads to wear and tear. No way around that. Hubs should be a maintenance item every 1-2 years for cars that see track use and aggressive driving.

Aggressive offset wheels that naturally have a spacer "built-in" will have identical characteristics to a wheel that runs a spacer once on the road. ET52 with a 25mm spacer fits the same as ET26 without a spacer (we're splitting hairs with that 1mm difference). Scrub, handling, feel, all the same.

Since this is all talk and myself prefer real-world examples, the GT350R comes from the factory with a 19x11" ET26 wheel that literally has a spacer built into the back side of the wheel. They come with long wheel studs, but still use a closed end lug nut because of how much room the "spacer" takes up. This is the exact same situation you end up with once you mount our ET52 wheel and a 25mm spacer.

Spacers are also used by many race teams to get the most wheel possible for the best performance. If it was dangerous or ill-advised, we wouldn't see them doing so. Here is Strom's PWC GTS Class M4 with a 30mm spacer.

Lastly, all of this spacer talk is centered around using the correct spacers. What is the correct spacer? One that is a pass-through design and slides over extended wheel studs, as shown above on the Strom BMW.

Below is an example of the wrong type of spacer. These bolt on spacers have no business being used on performance cars. Don't buy janky spacers, janky spacers are bad!

Hopefully this clears up some confusion and fear about spacers.

- Cory

 

[Xavierviana]

Wheel spacers are used for different purposes, some good and some bad. The general public has a fear of spacers and I'm not sure why, perhaps it's because they are not educated on their uses.

For Mustangs, we have an 11" wide wheel that has an offset of +52mm. We are also coming out with an 11" wide wheel that has an offset of +26mm. Why both? For starters, you cannot easily rotate your tires if you want to run an 11" square setup on the car, as the offsets are much different up front when compared to the rear. This leaves you with the option of having to dismount the tire from the wheel which is costly and time-consuming. If you run the same offset front and back with a spacer in the front, tire rotations are a breeze.

What exactly is it about spacers that are scary? Some have seen studs fail with spacers on them, but without analyzing the stud it's impossible to say that the spacer caused the failure. Unless the stud fracture occurred where the spacer meets the back of the wheel, the failure is not the fault of the spacer. Wheel bearings will not wear any different than a wheel with more offset built in. 11" wheels and subsequent tires generate a lot of grip, which leads to wear and tear. No way around that. Hubs should be a maintenance item every 1-2 years for cars that see track use and aggressive driving.

Aggressive offset wheels that naturally have a spacer "built-in" will have identical characteristics to a wheel that runs a spacer once on the road. ET52 with a 25mm spacer fits the same as ET26 without a spacer (we're splitting hairs with that 1mm difference). Scrub, handling, feel, all the same.

Since this is all talk and myself prefer real-world examples, the GT350R comes from the factory with a 19x11" ET26 wheel that literally has a spacer built into the back side of the wheel. They come with long wheel studs, but still use a closed end lug nut because of how much room the "spacer" takes up. This is the exact same situation you end up with once you mount our ET52 wheel and a 25mm spacer.

Spacers are also used by many race teams to get the most wheel possible for the best performance. If it was dangerous or ill-advised, we wouldn't see them doing so. Here is Strom's PWC GTS Class M4 with a 30mm spacer.

Lastly, all of this spacer talk is centered around using the correct spacers. What is the correct spacer? One that is a pass-through design and slides over extended wheel studs, as shown above on the Strom BMW.

Below is an example of the wrong type of spacer. These bolt on spacers have no business being used on performance cars. Don't buy janky spacers, janky spacers are bad!

Hopefully this clears up some confusion and fear about spacers.

- Cory

Cory,

I can not ask for more after your explanation.. crystal clear...

Thanks!!

 

[Grintch]

Correct offset ~ free
Big pass through/bolt through spacers (need new long wheel studs) - $400+
Janky bolt on spacers - $50+

Double if you run spacers front and rear.

 

[Apex Wheels]

Correct offset ~ free
Big pass through/bolt through spacers (need new long wheel studs) - $400+
Janky bolt on spacers - $50+

Double if you run spacers front and rear.

That's one way to look at it, but if you're serious about performance you need to run wide wheels. That leaves you with two options.
1. Run the same offset all around, requiring spacers and studs up front.
2. Run different offsets front and rear, requiring the tires to be dismounted, mounted, and rebalanced each time you want to rotate.

While there is more up front cost with the same offset wheels, it ends up being more affordable when compared to different front and rear offsets. Plus you gain strength with the ARP studs. It's not for everyone, and that's completely fine. But people need to understand the pros and cons of each scenario. "Correct" offset isn't always free.

 

[Grintch]

Arguably, if you are serious, budget is not much of a factor. And you buy the right wheels.

If you are less serious, a "true square" setup with 10 or 10.5" wheels is a lot cheaper than a 11" setup that requires big spacers up front. Partially because as you get to the bigger sizes, the tire cost really ramps up, and/or the selection gets very thin.

But we both agree that janky spacers are bad and bolt through spacers are acceptable.

 

[Apex Wheels]

I think anyone can appreciate some cost savings, but I see your point. There also aren't any 10.5" wide wheels that will fit without needing any spacers, unless you have the Cortex offset coilovers. The PF01's stick out a mile on the rear of 05+ Mustangs.

Glad we agree on the bolt on spacers

 

[Grintch]

People claim they fit (they are +38 right?). Someone else claimed that they were running a 10.5" +35. I have not seen either to verify, but plenty of people are running +35 10" wheels with no issues. So it doesn't seem like a giant stretch. I guess tires size also needs to be specified or understood to say if they work or not.

If only Apex would offer a good 10.5" alternative in a sea of 10 & (complicated) 11" choices.

 

[Apex Wheels]

The offset would need to be somewhere around +45 to fit the rear without sticking out, but then it would contact the front strut. An 18x10.5" ET38 would fit up front (very tight fit, with slight rubbing likely), but would stick out in the rear. Our 10" +40 is flush (assuming an average 285 tire like you alluded to).

Not to let too many secrets out but there are some plans for a 10.5" wheel, but there honestly is no way to make it not poke in the rear while also fitting up front on a stock-ish car. There will have to be a compromise somewhere.

 

[i4gains]

The offset would need to be somewhere around +45 to fit the rear without sticking out, but then it would contact the front strut. An 18x10.5" ET38 would fit up front (very tight fit, with slight rubbing likely), but would stick out in the rear. Our 10" +40 is flush (assuming an average 285 tire like you alluded to).

Not to let too many secrets out but there are some plans for a 10.5" wheel, but there honestly is no way to make it not poke in the rear while also fitting up front on a stock-ish car. There will have to be a compromise somewhere.

not to high jack this thread, Apex, your explanation of spacer use was phenomenal, ive always questioned those that automatically write off spacers as being viable.

Personal example. Im getting 19x10 +40mm with 255/40 /19 tires ( already had the tires) for my fitment to look flush, it sounds like ill need a 5 mm spacer. for daily driving, non track use, would any spacer be viable?

 

[Apex Wheels]

not to high jack this thread, Apex, your explanation of spacer use was phenomenal, ive always questioned those that automatically write off spacers as being viable.

Personal example. Im getting 19x10 +40mm with 255/40 /19 tires ( already had the tires) for my fitment to look flush, it sounds like ill need a 5 mm spacer. for daily driving, non track use, would any spacer be viable?

Thanks for the kind words. You will not need a spacer for it to be flush, however different people will have different definitions of "flush". Who's wheels are they? I'd encourage you to search online for those wheels mounted to cars without spacers and then determine if it's flush enough for you.

The +45mm offset I was referring to was for a 10.5" wide wheel. Also, you need to think of offset in opposite ideas, meaning that if you add a 5mm spacer to a wheel that has +40mm offset, the effective offset becomes +35mm. The more aggressive the offset is, the more it will stick out, and have a value that is closer to zero.

 

[i4gains]

not to sound cheap but i ordered xxr559 19x10 +40mm squared. i have coils and camber plates, id like a good mix of daily driver spec / a bit aggressive. im around 2 inches lowered on all 4 atm. but i might want something a tiny bit less aggressive. flush to me means, the tire sits just before or just even with the fender with little as possible wheel gap, without sacrificing the ability to go over speed bumps and slight grades with ease.

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