Do I need an alignment again if I got new tires?

[WarGin]

Hey guys, quick question.
Recently got an alignment for the first time since I got the jeep, after getting bigger tires then lifting it etc etc.
I wore my then new 31s down to nothing (fronts, on the inside of both tires),
They are literally 75% slick now. My fault , should've rotated them . Should've gotten it aligned a year ago.

So I got some new 31 MTs. I do not want them to wear out again. Do I need to get another alignment ? It hasn't even been a month since the first(and last) one. I'm trying to get at least 2 years or 40k outta them. Got 25 out of the old ones so I guess it wasn't too too bad. Planning on rotating every 5k.

 

[Keekleberrys]

As long as you haven't changed anything else steering or suspension wise you should be good.

 

[VAhasnoWAVES]

changing tire diameter will change toe. i would at least put a tape measure on it and double check...

if your not confident in doing that yourself, you said you bought NEW tires. most places will at least let you do a free alignment check, often doing alignment with new tires for free. cash in on that if you can.

 

[WarGin]

The new tires are from eBay so no free installation haha
They are both 31s, only the first are Federal Commando ATs,
And the new ones are Hercules Trail Digger MTs

Supposedly they are the same size, so I should, logically, be fine.
However the penny pincher in my head is freaking out because I expected more then a year from the Federals

 

[VAhasnoWAVES]

you dont think a set of bald tires are a different diameter than a new pair?

its probably negligible... but if your really worried, most places will still do a free alignment check. or for cheap insurance, you could take 5 minutes of your time to do measure and do a chalk test.

 

[old_man]

changing tire diameter will change toe. i would at least put a tape measure on it and double check...

if your not confident in doing that yourself, you said you bought NEW tires. most places will at least let you do a free alignment check, often doing alignment with new tires for free. cash in on that if you can.

SPOBI​

Since when will new tires change the toe?

 

[JWheeler]

changing tire diameter will change toe. i would at least put a tape measure on it and double check...

if your not confident in doing that yourself, you said you bought NEW tires. most places will at least let you do a free alignment check, often doing alignment with new tires for free. cash in on that if you can.

False. When you are not doing an alignment in your driveway, toe is typically measured in degrees. Not the distance between the tires. And the measurements are taken off the wheels.

 

[Cottontail]

I just paid Firestone to do lifetime alignments on my vehicle. Anytime I feel like I want or need an alignment, I just drop it off. I did that for all my Jeeps. Cheap and easy. I bought a lifetime on my ZJ in 1999 and 15 years later they are still doing my free alignments! Firestone lost cash money on me on that one - but they've probably earned it back 5x due to the people that I have sent to them!

 

[Tony_SS]

Tires costing so much, I think an alignment is money well spent. Most shops can at least check if for you w/o charging the full amount to do one.

 

[iluv83vettes]

SPOBI​

Since when will new tires change the toe?

When you measure incorrectly by measuring the distance difference front to rear and not the degrees of toe.

 

[clean4drxj]

If you're wearing the insides of the fronts, your caster is off or you have bad balljoints, check those first.

 

[yossarian19]

changing tire diameter will change toe. i would at least put a tape measure on it and double check...

I've seen this said before but it doesn't quite make sense to me. The manufacturer of every car I've seen gives alignment specs in degrees, not inches.
The tires are supposed to be at 1* toe in for part-time or 0* (straight ahead) for full-time, if I recall.
The angle doesn't change just because you have a larger tire - the edge of the tire is just closer to the point of intersection between the imaginary lines running from the hubs forward. As far as I can tell, this is irrelevant - provided the angles are correct. People use a tape measure and perform no math to check toe because it is convenient to get in the ballpark, not because it is correct.
Am I demonstrably wrong here?

 

[RoyalXJ]

Anytime I put new tires I always align it just to be safe. Nothing has probably change from the last time but you'll sleep easier knowing it's at least been checked.

 

[sidriptide]

spend the $$ on an alignment. go to Town Fair Tire, they dont do front-end work, so the bad parts they point out are legit. a solid front end is the key to avoiding all kinds of problems in the future.

 

[blondejoncherokee]

you can do your toe in in your garage in under 20 minutes by yourself. measure caster while you are at it with an angle finder

 

[Warlock1]

Hey guys, quick question.
Recently got an alignment for the first time since I got the jeep, after getting bigger tires then lifting it etc etc.
I wore my then new 31s down to nothing (fronts, on the inside of both tires),

When you do a lift on the front of these Cherokees with the stock steering components (inverted Y) it throws your toe way out of whack. The higher you go, the more toe in you get. Which is what happened to the tire in your pic. DAMHIK :gee:

You said you just had it aligned approx a month ago. Put your new (to you) tires on and be happy. As long as it has been properly aligned.

And by the way, adding whatever size tires will not change your toe settings, technically. The toe settings are for the stock size tires. If you go from the stock 27" tire to a 40" tire, the measurement for the toe setting might look like it has changed (which is what VAhasnoWaves was referring to), but it has not (in degrees). Since the diameter is larger for the 40" tire, you will necessarily get a higher or lower number when measuring because of the added length of the radius, but it is such a small amount of difference that it really doesn't matter. It is only a difference of, in this example, 13" total and 6.5" on each radius, which might make the original measurement of 0" to 1/16" look like 0" to 3/32". Not much difference.

And also, the factory front end toe in settings are 0" to 1/16" toe in. And yes, the factory uses the measurement of inches for toe in. It uses degrees for the caster and camber measurements. According to my factory service manuals.

 

[WarGin]

I asked around for a place that knew lifted vehicles, so I am confident that my jeep is currently correctly aligned.
Yeah, after lifting the car it really didn't take long to chew through those. At all.
I'm gonna try to get them mounted and balanced before Thursdays storm. The. I guess we'll see how they perform in the snow

 

[VAhasnoWAVES]

i did the math really quick...

1 degree of toe in results in :
.610" toe in on a 35" tire
.503" toe in on a 29" tire (thats stock right? its been so long...)

this is if you are measuring in your driveway. personally... i can catch 100 thou difference with a tape measure. considering the recommended tape measure alignment is 1/16-1/8" (.0625-.125") toe in, that seems excessive to me (the machinist in me says thats a mile). i do agree that toe on an alignment rack does get measure in degrees. ive bent a lot of steering and my driveway alignment always comes up green when i get it checked. now, will that 100 thou make your tires wear prematurely? i dont know... but my tires dont wear fast, funny, scallop, or cup... :dunno:

 

[yossarian19]

i did the math really quick...

1 degree of toe in results in :
.610" toe in on a 35" tire
.503" toe in on a 29" tire (thats stock right? its been so long...)

this is if you are measuring in your driveway. personally... i can catch 100 thou difference with a tape measure. considering the recommended tape measure alignment is 1/16-1/8" (.0625-.125") toe in, that seems excessive to me (the machinist in me says thats a mile). i do agree that toe on an alignment rack does get measure in degrees. ive bent a lot of steering and my driveway alignment always comes up green when i get it checked. now, will that 100 thou make your tires wear prematurely? i dont know... but my tires dont wear fast, funny, scallop, or cup... :dunno:

Thanks for doing the math to check up on that.

 

[5-90]

Hey guys, quick question.
Recently got an alignment for the first time since I got the jeep, after getting bigger tires then lifting it etc etc.
I wore my then new 31s down to nothing (fronts, on the inside of both tires),
They are literally 75% slick now. My fault , should've rotated them . Should've gotten it aligned a year ago.

So I got some new 31 MTs. I do not want them to wear out again. Do I need to get another alignment ? It hasn't even been a month since the first(and last) one. I'm trying to get at least 2 years or 40k outta them. Got 25 out of the old ones so I guess it wasn't too too bad. Planning on rotating every 5k.

If you need an alignment just getting new tyres, I think you have larger problems.

You can do the chalk strip test (same one you'd use to check ideal inflation pressure) to get an idea of whether or not you need an alignment to reflect the new tyres (just don't drive more than, say, 5-10 feet. You don't want to "wear away the high bits" to check pressure, you want to see how the line wears to get an idea. Can't do that if you wear the line away, you just want to turn the tyre all the way about once or twice. Make a thick stripe,) but if the alignment was done properly, I doubt you'd need to do it again.

Alternatively, look up the effects of malalignment on tyre tread (cupping, scrubbing, &c) and steering (failure to return to center, tendency to drift more than can be accounted for by the crown in the road,) as this will allow you to easily check the alignment yourself at intervals.