better all have the same tread depth.
They do. Measured em. Hpwever, Human error can be a factor, as with any measurement
buy my RA1’s. Brand new with the stickers on them.
Brandon this is a good idea. You put those on the vette and you might actually have good times at edinburg!! 
<3
WAIT.
You are going to have 2 tires the same outside dia, one random tire at another outside dia and yet another random tire at some point at again, another random dia?
BRO didnt we go over this already?
go do some math, find out how many RPM’s even 3/32’s of an inch difference will make in each gear at XX speed.
not only will your center dif hate life, but the front &/or rear will too!
Sell them to a RWD guy and get 4 NEW tires. If you cant afford $800 on 4 tires, you cant afford twice that for a diff replacement.
+rep
Ernie, once you get a full set you should sell them. You might even make a little money. Winter is right around the corner. Put the money toward snow tires.
I have six brand new Blizzaks. Dont need snows. All 3 tires are the same depth I measured. Dammit. I said that.
And realistically, these tires are gonna be on the car maybeeee a mile at speeds up to 60mph, but mostly slower. Not gonna hurt much even if they WERE different depths.
I know you said you measured them. For all we know you stuck lincolns head into the tread and drew a line with a sharpie! lol I assume you used the end of a digital caliper, or hope so.
You have to remember that your car has a lot going on under the surface. The small differences you dont think matter, really do!
I will prove it real quick. Once again, mechanical engineering kicks the shit out of shade tree logic.
The one on the left is a standard dia tire. 28" on the right is one 28.1" dia. Pshhhh .1" dat aint shiiiit right?
With the same gear ratios on both examples… look at what RPMS are needed at the crank to put out the same MPH per tire dia. 35RPM’s different to achieve the same MPH based on the roll out difference that lil .1" dia changed!
Sooo.
since your crank is of course not going to change RPM’s for each of the 4 unicorn tires you are putting on it… that will stay the same lets say 8285 Rpm like in my example.
tire 1 is on the front right 28" dia. Tire 2 is 28.1" on the left. tire 3 is brand new but such a great deal you got it anyway 28.2" on the left rear and the other 28" is on the right rear.
in a straight line the front and rear diffs will be slipping, and the center diff will be slipping to make up the 35 RPM difference. Now that needs to be computed in to the gear ratio for the diffs and all which I dont feel like going any deeper into this to prove myself.
Sure buzzing around an autocross track at limited speeds, might never know the difference by the seat of the pants, and you will prolly sell the car before the wear on the components will pop up. But it doesnt mean the little difference isnt going to hurt the car… you just dont know it!
naa i am done with all that stuff, i just want some tires for my z06 rims, i will hit the velley up a few times and spank your darkstar but thats about it. jiu-jitsu and training have taken up so much of my time i don’t have any to autocross, nore do i really care to.
You’ll be fine if they’re not all the same depth.
I believe most should know there is a 2% rule concerning depth of the tires. If all of your tires are within 2% OF CIRCUMFERENCE, you won’t have any issues. More than that, your diff won’t like you too much.
245/40-18 = 25.7
C=3.14*D
C=3.14*25.7
c= 80.698
2% of 80.698 is 1.613. So the C can go down to 79.085 without being an issue?
C= 79.085
X=79.085/3.14
X=25.1863
25.1863 = about a 225/40-18 (the 225 isnt JUST tread width as this shows)
so a 2% difference in C on a 245/45-18 is more than a half an inch DIA different, or .25" R.
thats a BIG difference. I pumped them into the same calculator I posted on page 2. It knocked off 4 mph in first, 13.6 in second, 22.59 in thrid and 26 in 4th… Thats a hefty difference. Actually 709RPM difference in 1st, one tire to the next. 1375 RPM’s different in 2nd gear one tire to the next. 1538 RPM difference in 3rd one tire to the next.
that 2% C, if my math is correct (might not be) is ALOT! Someone with more math skills than I have should put those into differential RPMS’s left vs right and front vs rear. I bets its a hefty amount of slippage going on there with .5" difference in DIA, which is the safe 2% C he stated.
If you have time to drag race, you have time to autocross…You havent been back since Miah beat you in your own car. Looks shady lol <3
But seriously, if its not for you then dont do it. But it would be cool if you came out and hung with us one of the days. Bring the wife 
Mike, I get your point. I get it. Really I do. I’ll even let you come measure the tires when you buy my FMIC!!
I am not busting your balls with the last post… or any of them really. Just putting up data supporting my theory. You could sell those to someone with a RWD track car just as easy as you bought them for I bet. then get a full set of used track tires from someone else. I cant buy the fmic, its a little too small for my needs, sorry bro.
Yes, I am positive it’ll be fine w/ a 2% circumference difference between front and back or side to side. Keep in mind what the whole meaning of a differential is… Pretty much to cope with difference tire speeds. I didn’t say that it wouldn’t cause any sort of stress, but the added stress is just the differential doing it’s job.
My 911 is AWD, and I have two drastically different tire sizes on it.
On the back, I have 315/30/18, which is an overall diameter of 25.5" and RPM of 816.
On the front, I will have to get back to you as I don’t remember, but the overall diameter (thus the RPM) is different than the back and the car has no problem. You can scour the internet all you want, but you’re going to get 20 different opinions from 20 different sources. Just going from my experience.
Gotcah there man. Its just in my opinion but its just un needed stress on the difs.
2012 911 4S
P235/35ZR19 front tires 25.5
P305/30ZR19 rear tires 26.2
almost 3/4" difference.
Fuck it I guess I am wrong. If the germans say its fine, it should be ok for the Japs! lol
:lol all that time posting math and lengthy explanations and you end up being wrong in the end anyway :rofl
Might have to set a character limit to posts :lol
I am not wrong. I just compromised! lol
Diff is still working overtime, I assume its a friction type in the evho, so technically speaking its putting un-needed wear and tear on it.
either way, we are both right, maybe kinda sorta.
ahh fuck it. :rofl
Lock up. Got #4