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Discussion Starter · #1 ·
I went from 17" Lexus wheels (225 45 17 tires) on all four axles to 18" Lexus wheels (225 40 18 tires) on the front and 18.5" Lexus wheels (255 40 18 tires) on the rear. After driving for 1 to 2 minutes I get a CHECK 4WD message. I have an 2007 IS250 AWD. Does Lexus need to reset something b/c the wheels are larger and/or staggered?...or is it something I can do?
 

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the difference in the diameter of the tires is probably what's causing it. not sure what to do about it or if there is a way to compensate for the difference.
 

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If it is anything like the Volkswagen you will need someone to flash your ecu into tricking it that the difference is not their. By going to a staggerred setup on an AWD car can also cause problems down the road in harsh driving situations (and sometimes jut normal driving situations depending on the setup). The differential is having to produce more power to the rear wheels with the difference of grip and weight. It sounds stupid but to give a for instance... Adding a staggerred wheel setup to a new Skyline will void your warranty for the same reason. It can also harm your car whether it be front or rear wheel drive to run a different sized tire/wheel on either side of the car. Another for instance.. On a Honda S2000 it states in big bold print that if you get a flat from one of your rear wheels to not run the spare on the rear. It is permissable but not often enforced by Honda to void your warranty for doing it. When looking into the whole thing try to look at it from an engineering stand point.

I would suggest that if you are running an AWD car to either look into another wheel choice non staggerred or to upgrade your drive train to compensate for the over working it will get from a staggerred setup and have your ECU flashed somewhere if possible. Guys running staggerred wheels on a VW R32 are normally replacing their Halidex system with an upgraded version in order not to screw up their drivetrain. Hope this helps and sorry to hear the setup is throwing codes.

I am assuming that since it says CHECK 4WD that your car is AWD of course lol.. And with that being said the slight difference in diameter size should not throw any codes. It may affect your spedometer slightly but once again no codes should be present due to this.

Forgot to mention also.. That on a VW R32 it has been known in some cases with a staggerred setup to throw the traction control light on due to what is discussed above.
 

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I went from 17" Lexus wheels (225 45 17 tires) on all four axles to 18" Lexus wheels (225 40 18 tires) on the front and 18.5" Lexus wheels (255 40 18 tires) on the rear. After driving for 1 to 2 minutes I get a CHECK 4WD message. I have an 2007 IS250 AWD. Does Lexus need to reset something b/c the wheels are larger and/or staggered?...or is it something I can do?
First, stop driving the car that way. NOW.

There's a reason Lexus offers that staggered 18" setup on every car except the AWD.

You will ruin the AWD system driving that way, and there's no "flash" for the ECU to fix it.

Any differential system expects the same diameter wheels on both sides of it. That's why a RWD car with a limited slip diff will ruin the LSD if he gets a flat and runs a different sized wheel on one side for a while.

And AWD car has a center differential, so you need the same overall diameter on all 4 wheels.

(there are ways to do that with a staggered setup, but not the factory 18s)


(I'd also suggest you switch the wheels back and reset the code before a dealer ever sees it, or you might no longer have a warranty on your transmission)
 

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Discussion Starter · #5 ·
My initial info was a little off. The diameters of the wheels are all 18" but the widths are different. The front are 18" by 8" and the rear are 18" by 8.5". Not sure if that changes your response above. If it comes down the tire size, then couldn't I just squeeze some 225 40 18 tires on the rear wheels? That way all the tires would be the same....or would they not fit on the wider wheels?
 

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im not sure you know what the tire size means. 225 is the width. 40 is the aspect ratio, meaning the height of the sidewall is 40% of the width, 90 mm in this case. 18 is obviously the wheel diamter. a 255 40 tire has a sidewall height of 102 mm, an overall diamter that is 24 mm larger than the front wheels. if you switch the rear tires to 255 35, the sidewall height is 89.25, MUCH closer to the front tires and probably within the tolerances of the drivetrain since it has to compensate for tire wear and manufacturing tolerances of tires.
 

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My initial info was a little off. The diameters of the wheels are all 18" but the widths are different. The front are 18" by 8" and the rear are 18" by 8.5". Not sure if that changes your response above. If it comes down the tire size, then couldn't I just squeeze some 225 40 18 tires on the rear wheels? That way all the tires would be the same....or would they not fit on the wider wheels?
Doesnt change the info I gave earlier sorry
 

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Doesnt change the info I gave earlier sorry
what do you mean? if the tires all have the same diameter, then the diff isnt working until the tires slip or until he turns. in slippery conditions where there is a difference in grip front to rear, yes the center diff will work harder. what i explained was to get all the tires roughtly the same diameter to get the error code to go away.
 

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First of all, the front tires are almost perfect sized, the rears how ever are an abortion of a sizing.

Compared to stock the new fronts are .44% off in size. (not 44, .44, less than 1)
Compared to stock the new rears are 4.08% off in size.

SO the rears are spinning waaay to slow to make the same speed. Solution? Buy the correct size for the rear. 255/35R18, that puts you within .192% (less than 1) of stock. which puts the difference at .248% so approximately 1/4th of a percent difference between front and rear. The speedometer at 60 will read less than 1/2 mph off (59.7 when actual vehicle speed is 60)


Dont do some dumb reflash or anything, do the right thing, buy the right tire size.
 

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You both are still missing the biggest factor in this equation. The car is AWD. It is not designed to run a staggerred setup. The whole flash of the ECu only was brought into a play if he decides to upgrade his drivetrain to compensate the abuse it is recieving from a staggerred setup which can ruin it.

Getting the tire size closer in te same diameter may clear the code but it will still affect the drivetrain.

Point is in the long run minus all the other info to the OP. Your stock drivetrain is not inteded to use a staggerred setup. Hence why the AWD IS did not come with a staggerred setup like the rear wheel drive version. Traction, weight, size, etc... are supposed to be the same all around. If you intend on running a staggered setup it is a good idea to updgrade your drivetrain.
 

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You both are still missing the biggest factor in this equation. The car is AWD. It is not designed to run a staggerred setup. The whole flash of the ECu only was brought into a play if he decides to upgrade his drivetrain to compensate the abuse it is recieving from a staggerred setup which can ruin it.

Getting the tire size closer in te same diameter may clear the code but it will still affect the drivetrain.

Point is in the long run minus all the other info to the OP. Your stock drivetrain is not inteded to use a staggerred setup. Hence why the AWD IS did not come with a staggerred setup like the rear wheel drive version. Traction, weight, size, etc... are supposed to be the same all around. If you intend on running a staggered setup it is a good idea to updgrade your drivetrain.


There is no way to flash the ECU.

There's also no "upgrades" made for the drivetrain.

Hence why your repeated suggestions to do either are kinda silly.

This isn't a volkswagon.

The OP needs to either run same (or very very very nearly same) overall diameter wheels/tires front and back or he needs to expect to replace his transmission very frequently and have a dash light on all the time.

Those are his only two options.
 

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There is no way to flash the ECU.

There's also no "upgrades" made for the drivetrain.

Hence why your repeated suggestions to do either are kinda silly.

This isn't a volkswagon.

The OP needs to either run same (or very very very nearly same) overall diameter wheels/tires front and back or he needs to expect to replace his transmission very frequently and have a dash light on all the time.

Those are his only two options.
First off, spell Volkswagen correctly.

Second, just because they dont make it for the mass market doesnt mean it isn't able to be done. Any one with money can get their drivetrain built. Do you think all cars just have parts for them right away. No someone has to develop them to solve a problem.

Third,there is always ways to trick ECU's into thinking its doing something that its not. Hence a flash. Just because it isnt a VW or hasnt been done does not mean it cannot be done. An ECU is simply a computer. Computers have codes. Codes can be changed. There is no arguing that. Do you think the first guy with a VW that got a fault code due to a mod said well crap there's no mass market for this guess Ill have to live with it. No. Properties can be changed and values can be changed in order to make the car do what you want it to do. This does take someone with skill, and it also takes money. BUT it CAN be done. An ECU flash is not a dumb idea, and neither is having someone upgrade the drivetrain to compensate for the weight and friction difference.

Lastly you are still missing the point. the car is NOT designed to run staggerred setup. Unless he finds a rear tire that weighs significantly less to make up for the weight difference in the rear wheels he is still affecting the drivetrain. But then again, that still leaves the rear wheels with a different coefficient of friction from the front wheels which once again is putting more force upon the differential.

Im not trying to be a jack*** or anything, but does no one understand how this stuff works? Do I need to draw you a diagram. I gave more examples than just a Volkswagen. Diameter is not the only thing factoring in this equation. Although it may get rid of his CEL for check 4WD it will not save his drivetrain. I am simply trying to help. Saying my ideas are "silly" isn't helping the OP with anything. I am on the same page in saying that the properly sized tire will more than likely fix the fault code, but it still isn't going to help save the drivetrain from being overworked.
 

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First off, spell Volkswagen correctly.
Why? Don't own one, never plan to. If they ever get outta the top 5 least reliable cars on JD Power maybe I'll start spell checking it.

Second, just because they dont make it for the mass market doesnt mean it isn't able to be done. Any one with money can get their drivetrain built. Do you think all cars just have parts for them right away. No someone has to develop them to solve a problem.
The only "problem" here is the OP doesn't understand how a differential works or the damage he's doing to his.

"Spend thousands of dollars for a custom drivetrain that will stand up to being abused" is a terrible answer for someone who just wants cooler looking wheels on their car and didn't realize the issues his choice might cause.


Third,there is always ways to trick ECU's into thinking its doing something that its not. Hence a flash. Just because it isnt a VW or hasnt been done does not mean it cannot be done. An ECU is simply a computer. Computers have codes. Codes can be changed. There is no arguing that.
Except it can't be done.

The USDM Toyota/Lexus ECU is heavily encrypted and can not be edited, changed, or flashed by anyone in the aftermarket. Period.

It's a dumb idea because it can't be done.

They can't even do it to Supra ECUs, which have been out since 1993, and where you might have heard there's a bit of interest in performance upgrades.



If someone could program Toyota/Lexus ECUs they'd have a license to print money as there'd be so many Supra, 1IS, 2IS, 1/2/3GS, SC, etc owners lined up outside their door for service.


The best you could do here to "fool" the ECU would be to build a computerized translator that lied about the data come from the wheel sensors. so that the ECU thought they were the same size.

This would be insanely dumb as it'd still ruin the drivetrain as well as throwing off VDIM/VSC and numerous other systems, but it's as close as you'd get to an ECU solution, and still isn't "flashing" it, because you can't.
 

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lol.. ok you win on the Volkswagen comment I actually laughed a little.

I will agree to some extent that I know of them having several problems but they are fun cars and some have seen several hundreds of thousands of miles.. I still have a place for them because they are fun for someone like me that likes to tinker with them.

As for the ECU goes, I was not aware of the encrypted information but once again you learn something new everyday. BUT.. someone smart enough could figure it out! The pentagon have guys that crack the most difficult codes on a daily occurance for national defense lol.. Im sure someone could do it.

But as for the OP not knowing what the staggerred setup is doing to the drivetrain that is why I consistantly stated that the whole point of what I was talking about was that he was hurting the drivetrain that was not designed to run staggerred. I dont see the sense of spending thousands upon thousands of dollars to upgrade his drivetrain but those are really his only two options. Upgraded the drivetrain and finding someone to either crack the code or run a standalone EMS that he can tell what the values are supposed to be which will be overly exspensive or to simply put a non staggerred setup on the car again so he doesnt ruin the drivetrain. I know the OP only wants to get rid of a code but I was trying to help with the real problem.
 

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First, stop driving the car that way. NOW.

There's a reason Lexus offers that staggered 18" setup on every car except the AWD.

You will ruin the AWD system driving that way, and there's no "flash" for the ECU to fix it.

Any differential system expects the same diameter wheels on both sides of it. That's why a RWD car with a limited slip diff will ruin the LSD if he gets a flat and runs a different sized wheel on one side for a while.

And AWD car has a center differential, so you need the same overall diameter on all 4 wheels.

(there are ways to do that with a staggered setup, but not the factory 18s)


(I'd also suggest you switch the wheels back and reset the code before a dealer ever sees it, or you might no longer have a warranty on your transmission)
First, stop driving the car that way. NOW.

There's a reason Lexus offers that staggered 18" setup on every car except the AWD.

You will ruin the AWD system driving that way, and there's no "flash" for the ECU to fix it.

Any differential system expects the same diameter wheels on both sides of it. That's why a RWD car with a limited slip diff will ruin the LSD if he gets a flat and runs a different sized wheel on one side for a while.

And AWD car has a center differential, so you need the same overall diameter on all 4 wheels.

(there are ways to do that with a staggered setup, but not the factory 18s)


(I'd also suggest you switch the wheels back and reset the code before a dealer ever sees it, or you might no longer have a warranty on your transmission)
I did my lexus gs350 awd 2009 front brake and rotors an drive it for 15min and cautions red light came on put the car in park an the dashboard said check AWD.
Don't no what happen need help thank you
 

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I did my lexus gs350 awd 2009 front brake and rotors an drive it for 15min and cautions red light came on put the car in park an the dashboard said check AWD.
Don't no what happen need help thank you
First, stop driving the car that way. NOW.

There's a reason Lexus offers that staggered 18" setup on every car except the AWD.

You will ruin the AWD system driving that way, and there's no "flash" for the ECU to fix it.

Any differential system expects the same diameter wheels on both sides of it. That's why a RWD car with a limited slip diff will ruin the LSD if he gets a flat and runs a different sized wheel on one side for a while.

And AWD car has a center differential, so you need the same overall diameter on all 4 wheels.

(there are ways to do that with a staggered setup, but not the factory 18s)


(I'd also suggest you switch the wheels back and reset the code before a dealer ever sees it, or you might no longer have a warranty on your transmission)
I did my lexus gs350 awd 2009 front brake and rotors an drive it for 15min and cautions red light came on put the car in park an the dashboard said check AWD.
Don't no what happen need help thank you
First, stop driving the car that way. NOW.

There's a reason Lexus offers that staggered 18" setup on every car except the AWD.

You will ruin the AWD system driving that way, and there's no "flash" for the ECU to fix it.

Any differential system expects the same diameter wheels on both sides of it. That's why a RWD car with a limited slip diff will ruin the LSD if he gets a flat and runs a different sized wheel on one side for a while.

And AWD car has a center differential, so you need the same overall diameter on all 4 wheels.

(there are ways to do that with a staggered setup, but not the factory 18s)


(I'd also suggest you switch the wheels back and reset the code before a dealer ever sees it, or you might no longer have a warranty on your transmission)
And all so rotors are sport performances
 
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