Using OEM rear 8.5 wheels on the front

[Yojimbo]

Been debating going with a square setup for my car. I currently have the 8 inch front wheels with the 8.5 rears. I was debating buying another set of rear wheels off marketplace for cheap and running the 8.5s up front. I know I will need spacers due to the offset difference. I'm just curious if someone else has done something similar as well?

 

[Snicklefritz]

more than someone has done this. but I haven't heard of it for quite a while. you'll need a good 10mm spacer at least, iirc reading about it.

 

[Yojimbo]

more than someone has done this. but I haven't heard of it for quite a while. you'll need a good 10mm spacer at least, iirc reading about it.

Will definitely get the spacers if I go that route. Was thinking 15mm should sit just right, would probably run 15mm spacers in the rear too while im at it. Its been kind of a pain finding nice wheels for this car that aren't black, and the OEM ones suit the car really well. Would probably get them refinished in a bronze if I go through with it

 

[Volfy]

If you are going to get them refinished too, you'll likely spend as much as, if not more than, a set of aftermarket wheels.

 

[Yojimbo]

If you are going to get them refinished too, you'll likely spend as much as, if not more than, a set of aftermarket wheels.

You are right. The only issue is I'm having a real hard time finding something that works for the car in the right color. If I get the wheels refinished then I can choose whatever I want. But I might also just run what I have now as my winter wheels and run spacers on the 8.5s when I rotate tires. Not sure how 8.5 fronts and 8 rears would affect anything, but I know 245/35/19 tires would work on both sets.

 

[Snicklefritz]

Not sure how 8.5 fronts and 8 rears would affect anything, but I know 245/35/19 tires would work on both sets.

other than a small amount of more sidewall stretch on the 8.5 what would look different with 245 at all four corners? the offset of the 8.0 is 34, and that pushes the rim out quite a bit, but you have a narrower tire on than staggered oem. one thing that is affected by going square 245, you are reducing understeer at both ends by running wider in front and narrower in back, but I bet you'd have to push it pretty hard in a corner to notice the reduced understeer. maybe you'd experience oversteer?

 

[Yojimbo]

other than a small amount of more sidewall stretch on the 8.5 what would look different with 245 at all four corners? the offset of the 8.0 is 34, and that pushes the rim out quite a bit, but you have a narrower tire on than staggered oem. one thing that is affected by going square 245, you are reducing understeer at both ends by running wider in front and narrower in back, but I bet you'd have to push it pretty hard in a corner to notice the reduced understeer. maybe you'd experience oversteer?

So I am actually currently running the 245 tires all around. Honestly, I have not noticed any difference in every day driving. These are also my winter tires, so I expect them to have a bit less grip than the summer ones. I know that 8.5" in the front and 8" in the back should work, but part of me can't seem to accept the idea of running my wider wheels up front lol.

At the same time, I'm really wondering if rotating tires will actually make much of a difference. This is my first AWD car, all the ones I had before were FWD. I know of all the benefits of rotating tires and how it can help in getting more life out of your tires, but does it really make THAT big of a difference to even bother? I have never not rotated tires so I don't actually know what the savings would actually be like if I didn't.

Another option and probably the most pain in the ass for my shop is to just remove the tire entirely and swap them around. That way I keep the wheels where they should be, but I'm still rotating my tires.

 

[Snicklefritz]

I know that 8.5" in the front and 8" in the back should work, but part of me can't seem to accept the idea of running my wider wheels up front lol.

me too, I'd not do it because it isn't aesthetic and even if nobody else knew the wider rims are in front it would bother me no end.

At the same time, I'm really wondering if rotating tires will actually make much of a difference. This is my first AWD car, all the ones I had before were FWD. I know of all the benefits of rotating tires and how it can help in getting more life out of your tires, but does it really make THAT big of a difference to even bother? I have never not rotated tires so I don't actually know what the savings would actually be like if I didn't.

Another option and probably the most pain in the ass for my shop is to just remove the tire entirely and swap them around. That way I keep the wheels where they should be, but I'm still rotating my tires.

you don't want to pull the tires and remount them every rotation, bad for the wheels cosmetically, can't be good for the tires either. this awd car is my first and I also have true rotational wheels, they are staggered and limited to one side of the car. it's aesthetics again, only a car enthusiast would notice if the wheels were mounted on the wrong side of the car, it wouldn't have any operating effect to put them on the wrong side of the car. but the point Ima making is that I don't even swap wheels from one side to the other, forget rotating. and I see maybe a thousand miles at the end of the life of the tire. as long as alignment is good the wear will be pretty even, barring a lot of hard cornering on cloverleafs, of course, my front left tire outer wear is always the first thing to go.

 

[Yojimbo]

me too, I'd not do it because it isn't aesthetic and even if nobody else knew the wider rims are in front it would bother me no end.

you don't want to pull the tires and remount them every rotation, bad for the wheels cosmetically, can't be good for the tires either. this awd car is my first and I also have true rotational wheels, they are staggered and limited to one side of the car. it's aesthetics again, only a car enthusiast would notice if the wheels were mounted on the wrong side of the car, it wouldn't have any operating effect to put them on the wrong side of the car. but the point Ima making is that I don't even swap wheels from one side to the other, forget rotating. and I see maybe a thousand miles at the end of the life of the tire. as long as alignment is good the wear will be pretty even, barring a lot of hard cornering on cloverleafs, of course, my front left tire outer wear is always the first thing to go.

One thing I'm not sure about is if my summer tires can be rotated side to side. They are Bridgestone Potenza re980as. But for the winter I know they are directional and the only way to rotate them is to switch them front to back. So I will either not rotate tires, or suck it up and put the wider tires up front.

Maybe I will test out not rotating tires for once and see if it really matters. If it doesn't then I for sure will go with some nice fat wheels/tires in the back when I go aftermarket lol

 

[Landshark]

This is my first AWD car, all the ones I had before were FWD. I know of all the benefits of rotating tires and how it can help in getting more life out of your tires, but does it really make THAT big of a difference to even bother?

the main reason for rotating tires on an AWD car is so you keep wear even and don't jack up the drivetrain. didn't feel like typing a big long explanation, so i copy n pasted this LOL:

"a difference in diameter of less than half an inch between front and rear tires on your AWD can mean trouble for the drivetrain, the parts of the car that transfer the power to move the vehicle forward.

Parts of the drivetrain Source: Drivetrain This is because the heat that builds up from the effort of the smaller tires “trying to keep up” creates stress on the transmission and axles that can result in expensive repairs.

Second, if the two tires on one axle are spinning faster than the others, your car’s electronics may think those are slipping, and put you in the wrong gear. Most AWD systems in today’s cars include sensors on each wheel that monitor traction and wheel speed hundreds of times per second. This is what allows the AWD system to work in slick conditions, by sending power to whatever wheel(s) have the most traction.

When smaller tires are spinning faster, the system may put your vehicle into four-wheel lock, the gear that’s used for driving in slippery conditions. That’s a no-no, since driving in that mode on pavement or at speed can cause damage to your car."

short answer - if one end of the car's tires wear significantly more than the other, your transmission or other drivetrain components may require you to throw large amounts of money at them ... some cars are more senstive to this than others - Subarus, for example, are on the pickier end of having close tolerances.

 

[Snicklefritz]

short answer - if one end of the car's tires wear significantly more than the other, your transmission or other drivetrain components may require you to throw large amounts of money at them ... some cars are more senstive to this than others - Subarus, for example, are on the pickier end of having close tolerances.

my experience with the staggered wheels of the stinger is that it's not picky. I've worn two rear 255s out for each front 225 set, and also put brand new 225s on with worn 255s and never had any problems.

 

[Volfy]

Kia, as a mfr, understands that even if all 4 tires are correctly sized per their specifications, there are a host of "real-world" factors that might change their effective rolling diameters, when actually driven on the road:

1. Varying tire pressures
2. Uneven tire wear
3. Uneven load (e.g. heavily loaded rear end with cargo/passenger)
4. Different mfr/model of tires
5. Varying alignment settings (e.g. camber angles)
6. Vehicle speed (ballooning at higher speeds, due to centrifugal force)

So... they typically factor in enough allowable variance to account for a combination of all these factors. They cannot possibly make their AWD TC/ESC algorithms so touchy, to a point of not tolerating these real-world variances, lest they wish to deal with customer complaints from just normal usage.

How folks get in trouble is when they start changing tire sizing, either for aesthetic or performance reasons, such that the front and rear rolling diameters no longer match - even before factoring in the above factors. That, would be a big no-no. You can eat up only so much of the inherent mfr tolerances, before any of the above variances will trigger a fault.

So the moral of the story is... if yours is an AWD:

1. Stick to the mfr specs on rolling diameter as closely as possible.
2. If you do change tire sizing, match front and rear diameter as closely as possible.
3. Regardless of tire sizing, pay attention to your tire pressures.
4. If you have a penchant for high speed, be especially cautious on your tire choice, as different speed rating tires (e.g. H,V,W, Z, etc.) will vary in their ability to cope with high speed ballooning.
5. Don't do stupid s*** like cranking up HUGE negative cambers

 

[Landshark]

my experience with the staggered wheels of the stinger is that it's not picky. I've worn two rear 255s out for each front 225 set, and also put brand new 225s on with worn 255s and never had any problems.

haven't had the Stinger for that long, so i'm no expert on its AWD system. if i'm not mistaken, the Stinger is more of a Haldex-type system, where its mainly RWD until needed, then fronts kick in? i've had other cars with a more "full-time" AWD - had to be more careful with them - you didn't replace one tire if it got messed up, you replaced all of them.

 

[Yojimbo]

Ah man... So much knowledge. I sort of agree with everyone. My initial idea with the car was to just sell the wheels entirely and get two sets of squared sets. One cheap one for winter and one nicer one for summer. Only issue is, these wheels don't really fit on much else besides a G70 so I don't know if I would even be able to sell them, so I figured they could be my winter wheels.

the main reason for rotating tires on an AWD car is so you keep wear even and don't jack up the drivetrain. didn't feel like typing a big long explanation, so i copy n pasted this LOL:

"a difference in diameter of less than half an inch between front and rear tires on your AWD can mean trouble for the drivetrain, the parts of the car that transfer the power to move the vehicle forward.

Parts of the drivetrain Source: Drivetrain This is because the heat that builds up from the effort of the smaller tires “trying to keep up” creates stress on the transmission and axles that can result in expensive repairs.

Second, if the two tires on one axle are spinning faster than the others, your car’s electronics may think those are slipping, and put you in the wrong gear. Most AWD systems in today’s cars include sensors on each wheel that monitor traction and wheel speed hundreds of times per second. This is what allows the AWD system to work in slick conditions, by sending power to whatever wheel(s) have the most traction.

When smaller tires are spinning faster, the system may put your vehicle into four-wheel lock, the gear that’s used for driving in slippery conditions. That’s a no-no, since driving in that mode on pavement or at speed can cause damage to your car."

short answer - if one end of the car's tires wear significantly more than the other, your transmission or other drivetrain components may require you to throw large amounts of money at them ... some cars are more senstive to this than others - Subarus, for example, are on the pickier end of having close tolerances.

haven't had the Stinger for that long, so i'm no expert on its AWD system. if i'm not mistaken, the Stinger is more of a Haldex-type system, where its mainly RWD until needed, then fronts kick in? i've had other cars with a more "full-time" AWD - had to be more careful with them - you didn't replace one tire if it got messed up, you replaced all of them.

I agree with all you mentioned up top. I know the reason for it, I will monitor the wear on my tires when I swap back to the summers. If there aren't any issues, I honestly might just run the tires without rotating until they're finished, then I can figure out which direction I'll go. I also have not had my car that long, about 8 months, I believe you are right about the haldex type system. I remember seeing it somewhere that the car is mostly RWD until it needs the grip. But I could also be wrong on that.

my experience with the staggered wheels of the stinger is that it's not picky. I've worn two rear 255s out for each front 225 set, and also put brand new 225s on with worn 255s and never had any problems.

That's basically how I've done it with my previous cars, but those were always square setups. Just swapped out the one side that would need it, obviously would swap two tires at a time when required.

Kia, as a mfr, understands that even if all 4 tires are correctly sized per their specifications, there are a host of "real-world" factors that might change their effective rolling diameters, when actually driven on the road:

1. Varying tire pressures
2. Uneven tire wear
3. Uneven load (e.g. heavily loaded rear end with cargo/passenger)
4. Different mfr/model of tires
5. Varying alignment settings (e.g. camber angles)
6. Vehicle speed (ballooning at higher speeds, due to centrifugal force)

So... they typically factor in enough allowable variance to account for a combination of all these factors. They cannot possibly make their AWD TC/ESC algorithms so touchy, to a point of not tolerating these real-world variances, lest they wish to deal with customer complaints from just normal usage.

How folks get in trouble is when they start changing tire sizing, either for aesthetic or performance reasons, such that the front and rear rolling diameters no longer match - even before factoring in the above factors. That, would be a big no-no. You can eat up only so much of the inherent mfr tolerances, before any of the above variances will trigger a fault.

So the moral of the story is... if yours is an AWD:

1. Stick to the mfr specs on rolling diameter as closely as possible.
2. If you do change tire sizing, match front and rear diameter as closely as possible.
3. Regardless of tire sizing, pay attention to your tire pressures.
4. If you have a penchant for high speed, be especially cautious on your tire choice, as different speed rating tires (e.g. H,V,W, Z, etc.) will vary in their ability to cope with high speed ballooning.
5. Don't do stupid s*** like cranking up HUGE negative cambers

Agreed with that, I always stick as close as possible to the OEM diameter specs and I literally check my tire pressure every time I get in the car lol. I always buy tires that are one rating higher than what I actually need, as much as I like to speed, I want to make sure the things making contact with the road can handle anything I do. The one thing I will be doing is lowering my car using the ARK GTF lowering springs, so I will have to keep an eye on things once that is done to make sure tires aren't getting worn down unevenly.

 

[Snicklefritz]

haven't had the Stinger for that long, so i'm no expert on its AWD system. if i'm not mistaken, the Stinger is more of a Haldex-type system, where its mainly RWD until needed, then fronts kick in? i've had other cars with a more "full-time" AWD - had to be more careful with them - you didn't replace one tire if it got messed up, you replaced all of them.

yes, good point, that dovetails with what @Volfy said about designed-in 'allowable variances'. some of used to think that comfort mode was 50/50 power split, but the stinger is rear drive biased and is apparently 40 front 60 rear as the most even split, with 20 front and 80 rear in sport, so, you're right about that, whatever a 'haldex type system' is, Ima guessing it isn't rwd biased. the awd k5 is front wheel drive biased I believe and on a very puny east-west engine layout, not at all what we are talking about the stinger.

 

[Landshark]

whatever a 'haldex type system' is, Ima guessing it isn't rwd biased. the awd k5 is front wheel drive biased I believe and on a very puny east-west engine layout, not at all what we are talking about the stinger.

i guess i was referring to it being an "on-demand" AWD system ... "Haldex-type" was the wrong term for me to use as those are FWD based.

 

[moinmoin]

Been debating going with a square setup for my car. I currently have the 8 inch front wheels with the 8.5 rears. I was debating buying another set of rear wheels off marketplace for cheap and running the 8.5s up front. I know I will need spacers due to the offset difference. I'm just curious if someone else has done something similar as well?

What you are debating I did a couple of years ago. My first set of Michelin A/S lasted only 30K kilometers or 18600 miles. I bought a second set of OEM Stinger rims and now run Michelin A/S tires (255/40) as a square setup on the 8.5" rims and will eventually put snows (225/45) squared on the 8" rims.
Currently I have other vehicles with snow tires that I drive when the weather demands it.

The second set has been on the car for 32K now and there is a good chance these tires will last another couple of seasons. Whether they'll give me the 70K Michelin is warranting remains to be seen, but it is already a substantial improvement. I change my oil every 5K and rotate the tires at the same time, alternating between front to back and crosswise. And while the tire are off, my mechanic will service the brakes to the extend required.

Have a look and my post here:

Wheel/size/offset and tire/size/profile...can be confusing.
post 441

 

[Yojimbo]

What you are debating I did a couple of years ago. My first set of Michelin A/S lasted only 30K kilometers or 18600 miles. I bought a second set of OEM Stinger rims and now run Michelin A/S tires (255/40) as a square setup on the 8.5" rims and will eventually put snows (225/45) squared on the 8" rims.
Currently I have other vehicles with snow tires that I drive when the weather demands it.

The second set has been on the car for 32K now and there is a good chance these tires will last another couple of seasons. Whether they'll give me the 70K Michelin is warranting remains to be seen, but it is already a substantial improvement. I change my oil every 5K and rotate the tires at the same time, alternating between front to back and crosswise. And while the tire are off, my mechanic will service the brakes to the extend required.

Have a look and my post here:

Wheel/size/offset and tire/size/profile...can be confusing.
post 441

Oh my god! I have finally found you! I have been reading through that form for months now and somehow missed your post. Thats exactly what I wanted to do. You have convinced me and I will most likely go this route as well. Now I just have to debate using these all year around or using them as my winter wheels only.

Appreciate the info!

 

[moinmoin]

Oh my god! I have finally found you! I have been reading through that form for months now and somehow missed your post. Thats exactly what I wanted to do. You have convinced me and I will most likely go this route as well. Now I just have to debate using these all year around or using them as my winter wheels only.

Appreciate the info!

Glad to be of assistance.

Just to clarify: I have two OEM sets of rims, i.e. 4 @ 8" and 4 @ 8.5"

I use the 8.5" for summer and the 8" for winter driving. If you have two full sets, you can do the same. You may know, that narrower tires are preferable for winter driving.

I increased the aspect ratio of my tires by 5% - so instead of 255 35 I run on 255 40. The difference causes the car's speedometer to e "slow" by about 4%, so instead of 100, your real speed would be +- 104. My GPS provides true speed. But the added sidewall I think has saved my rims from getting damaged in potholes and such several times. And it adds comfort to the way the car rides.

Good luck with your decisions.

 

[Yojimbo]

Glad to be of assistance.

Just to clarify: I have two OEM sets of rims, i.e. 4 @ 8" and 4 @ 8.5"

I use the 8.5" for summer and the 8" for winter driving. If you have two full sets, you can do the same. You may know, that narrower tires are preferable for winter driving.

I increased the aspect ratio of my tires by 5% - so instead of 255 35 I run on 255 40. The difference causes the car's speedometer to e "slow" by about 4%, so instead of 100, your real speed would be +- 104. My GPS provides true speed. But the added sidewall I think has saved my rims from getting damaged in potholes and such several times. And it adds comfort to the way the car rides.

Good luck with your decisions.

What I think I will do is keep these as my winter wheels and sell the two 8 inch wheels that remain, or just store them just in case they're needed later. I think I will stick to the 35 sidewall, I usually like to stick within 3% on the revs per mile scale, just so the speedo isn't so far off.

If I do what you did and have two full sets, I fill probably get the 8.5s refinished in a different color. So many decisions, and so much money to be wasted.

Thanks again!