Changing just 2 tires?

[HardDrive]

My wife's Lexus had an alignment issue in the front. The front tires got worn badly, while the rears are in good shape, at least 50% tread.

Would you have any reservations about changing the 2 worn tires, and not all 4? I'm only asking because years ago I have tech (who might have been full of baloney) tell me that having uneven tires can cause problems with the stability control system. Anyone heard of such a thing?

[stomachmonkey]

Following that logic you would be having problems now, right?

It would seem to be an issue for everyone who did not routinely rotate tires.

[Steve Carlton]

If the car is 2 wheel drive, I wouldn't worry about it. I'd try to match the tire exactly if possible and put the new ones on the front so the rears will last longer.

[wdfifteen]

Depending on the kind of tire pressure monitoring you have it could set your warning light off more often. Anything - like the stability control, ABS, and some TPM systems - that depend on measuring relative wheel speed can be affected. But, like the monkey said, if it isn't acting up now, it probably won't act up with new front tires vs worn front tires.

What is TPMS & How Does it Work? | Bridgestone Tires

[foxpaws]

If it is AWD you will need to replace all 4 tires - you can damage the center diff if you don't. You could shave them to match the diameter of the old tires - but, that is still sort of iffy. 2WD and 4WD are usually OK with only 2 tires being replaced.

[Steve Carlton]

Depends on the type of AWD. Subaru's AWD is very unforgiving of tire circumference differences, whereas Haldex systems are pretty easy going. I've had great luck shaving new tires on the Subaru I had, but it was a good shop that worked on race cars. They shaved the new tire to somewhat varying depth across the tread to match the other tires perfectly.

[island911]

Originally Posted by foxpaws

If it is AWD you will need to replace all 4 tires - you can damage the center diff if you don't. You could shave them to match the diameter of the old tires - but, that is still sort of iffy. 2WD and 4WD are usually OK with only 2 tires being replaced.

Passing on the words of a tire salesman, eh? Those guys gave up careers in rocket surgery to save the center diffs, right?

IOW, If that were true, every truck, with a heavy engine over the (lower pressure) front tires and little weight over the rears would be grenading center diff's.

IOW 2, the effective radius, due to tire pressure, varies more than a 32nd of wear . . .and still center diffs handle it with ease. If that scares you, do NOT do the math on difference in radii of going around corners - else you'll never steer again.

Bottom line: put the new ones on (I would put them up front) and move on.

Edit: So, yes, HD, you are smart to consider that the tech might have been full of baloney.

[foxpaws]

Originally Posted by island911

Passing on the words of a tire salesman, eh? Those guys gave up careers in rocket surgery to save the center diffs, right?

IOW, If that were true, every truck, with a heavy engine over the (lower pressure) front tires and little weight over the rears would be grenading center diff's.

IOW 2, the effective radius, due to tire pressure, varies more than a 32nd of wear . . .and still center diffs handle it with ease. If that scares you, do NOT do the math on difference in radii of going around corners - else you'll never steer again.

Bottom line: put the new ones on (I would put them up front) and move on.

Edit: So, yes, HD, you are smart to consider that the tech might have been full of baloney.

Nope, working in alignment and with ASE techs for 20+ years - and seeing Subie after Subie, along with a few others (yes a Toyota Landcruiser 100 - same as a Lexus LS470) with damaged center diffs which happened after the owners replaced 2 tires.

AWD is significantly different than your 2WD/4WD trucks that you are talking about it.

Edit - checked with the guys in the back - a Highlander (which I think is about a RX 450) not a Landcruiser - my error.

[wdfifteen]

Originally Posted by island911

IOW, If that were true, every truck, with a heavy engine over the (lower pressure) front tires and little weight over the rears would be grenading center diff's.

How many trucks have AWD??

[island911]

Originally Posted by foxpaws

Nope, working in alignment and with ASE techs for 20+ years -...

Wow. So then YOU gave up a career in rocket surgery to save the center diffs.

If a car has a POS center diff, then that is the problem. Not the tire tread depth. --tho, I expect that the owner is easily blamed.

HD has a Lexus here. AND he is asking about stability control system potential problem. --no need for straw car builds here.

[herr_oberst]

Archipelago never misses a chance to display a little vitriol.

[kang]

Putting new tires on the front only can be dangerous. They will have more traction than the worn old rear tires. This means the rear tires will loose traction first. Can you say oversteer? Think rain, sand, gravel, any low traction situation. For someone not familiar with oversteer, this can be a very bad thing. I know someone who oversteered off a mountain road and rolled their SUV because they but new tires on the front only. Luckily they escaped with bruises only, but SUV was totaled.

If your wife's Lexus has the same size tires front and rear, put the worn rear tires on the front and the new tires on the rear. If it doesn't have the same size tires, replace all four.

[RANDY P]

It's not gonna hurt anything. Run the same make and size, when the others wear, change them.

If you run different sizes, or different types of tires, yes. however, even a difference of 5% in diameter isn't going to freak it out.

People have been doing that crap for years to cars just to save $$$$- BMW notably 245/40 in front.

rjp

[wdfifteen]

Originally Posted by herr_oberst

Archipelago never misses a chance to display a little vitriol.

Foxpaw's post is the only reason he and Randy are here. Foxpaw draws the flies from PARF like sugar.

[RANDY P]

Originally Posted by wdfifteen

Foxpaw's post is the only reason he and Randy are here. Foxpaw draws the flies from PARF like sugar.

Boy, someone has a woodie this morning.

Check to see how many responses to FP I've given in the last 500 posts. You might also bother to read what I said. You might learn something new.

BTW - BTDT on an AWD Trailblazer SS, and I pay attention to such small details.

Now, quit PARF'ing this thread.

rjp

[Steve Carlton]

Originally Posted by kang

Putting new tires on the front only can be dangerous.

"Can be" are the operative words here. HD's Lexus has more than 50% tread on the rear and I'm not advocating putting the new tires on the front AND leaving them there permanently. I'm an advocate of rotating tires every 5,000 miles or so.

[74-911]

I just had to replace the rear tires on wife's Jetta. Discount Tire states up front that if you replace 2 tires, for safety reasons they will only mount the new tires on the rear....

[foxpaws]

Originally Posted by Steve Carlton

"Can be" are the operative words here. HD's Lexus has more than 50% tread on the rear and I'm not advocating putting the new tires on the front AND leaving them there permanently. I'm an advocate of rotating tires every 5,000 miles or so.

Really important - far more than people seem to realize - the guys here rotate my tires every oil change - they last a long, long time (but it also goes to alignment school a couple of times a year, so that probably adds to the longevity of my tires).

So, you shaved the tires for your subie - I thought about doing that with my daughter's but, when I figured out I would be sacrificing a little over 25% of the thread, along with the $17.50 per tire to get them shaved (by a good shop), plus I could sell the 2 'good' tires for $25, it seemed more cost effective to get new tires on all 4 corners.

And 2 new tires mount on the rear - let them scuff up some, and wear a little before you put them on the front.

[island911]

Originally Posted by wdfifteen

Foxpaw's post is the only reason he and Randy are here. Foxpaw draws the flies from PARF like sugar.

The reason I chimed in was for the OP, HD. He's a good guy -used be local here- and doesn't deserve the miss-information being served. So quit being a protectionist tool for miss (information) paws..

[RANDY P]

...actually I was trying to correct WD- that's who I was referring to.

TPMS has NOTHING to do with OD. Does 40PSI in a 245 change compared to 40PSI in a 255?

rjp

EDIT: Maybe it DOES- Social Justice, YO. 245 has less than 255- it ain't equality!