How to Calculate the PERFECT Tire Stretch

How to Calculate the PERFECT Tire Stretch

– – [Alex] Hey guys what’s going on? It’s Alex from Fitment Industries and today
we’re gonna be talking about one of the most hotly debated conversation starters, questions,
comments, things that you guys ask us about nothing more than stretched tires. Now before we get into it we do wanna say
our lawyers made us say this because they’re boring and lame and get they paid way more
than I do that if you stretch your tires you do have to remember that you increase the
risk of debeading your tire and safety. So be sure that if you’re going to stretch
your tires that we are out of the mix when it comes down to liability in whether you
choose to do it or not is entirely your call. Whether you choose to purchase them or not
is entirely your call. We are just here to tell you how to calculate
stretch but once you do the purchase and the things with the stretched tires completely
out of our control. We’re gonna pretend like we don’t even know
you. Before we get into it don’t forget to subscribe. I’m Alex from Fitment Industries and let’s
get right into it. When you calculate stretch it’s very difficult
to do. Now we have a calculator and different things
on our set. We even have a gallery where we can look and
see what stretched tires look like. But at the end of the day, it’s very hard
to actually calculate stretch. Everybody has a different definition of what
a stretched tire is. So we decided to browse the forums, browse
Facebook and ask a bunch of people, cause we you know we know a couple people, on how
they calculate stretch and how people like just you and me can get down to it and figure
how to calculate stretch with nothing more than pretty much a pencil and a piece of paper. And we did. So we wanted to give credit to the guy named
H3LLK1T3. He’s on a forum that actually calculated stretch
and found a very good way to go about it that we wanted to pass on to you guys. So again H3LLK1T3, I don’t know his actual
name, thank you for doing all the work that you did. We are going to help these guys figure out
how to calculate stretch as well. And we will actually drop the original thread
in a post description thing below. But of course let’s get right into it. So this system is gonna work for most wheel
set ups. Now diameter really doesn’t matter so if you
have a thirteen or a twenty three it’s not gonna change anything. What is gonna change is the width and we’re
gonna get into that. We’re gonna break this down into what we call
stages so we’re gonna have stages of stretching from down all the way up in terms of “meaty”
stretches. So we’re gonna start off with just the basics
which is a two fifty five thirty five tire on an 18X10. So a two fifty five thirty five tire on an
18X10 is actually almost the exact perfect set up for a square set up. If you take the two fifty five, you turn that
into inches, you’re getting roughly around ten inches exactly and that thirty five side
wall is almost identically perfect to a straight up and down side wall on a ten wide. And with how we do the stages, you use the
two fifty five thirty five on an 18X10 to essentially set up your base line, where if
we go down an aspect ratio or we go down a tire size that’s how we’re going to get our
stages of stretching. And if we go up in tire size or we go down
in width but we stay in our tire size in terms of a wider tire smaller width wheel, we also
get that meaty stage set up as we go into the future. So the two fifty five thirty five is what
we’ll call a stage zero. It’s a neutral spot for you to calculate your
stretch. Now if you go into how you’re going to go
down, you’re gonna wanna remember that section changes go in intervals of ten, and side volt
changes in interval of five. Meaning if you go from a two fifty five to
a two forty five that is one stage of stretch. If you go from a two fifty five thirty five
to two fifty five thirty, that is also one stage of stretch so just take that into consideration. A two forty five thirty five on a ten wide
would be a stage one stretch, that would be a mild stretch. A two thirty five thirty five on a ten wide
would be a stage two stretch. On a two twenty five thirty five you’d be
looking at a stage three which would be a full stretch. Now that would be about as far as you could
actually go in terms of stretching out your tires. There’s very few tires you can go to a stage
four. And by then you are dealing with some severe
debeading issues and a whole bunch of mess that we will not even get into. Now if we go back you can actually run a two
twenty five forty which brings you back up to stage two stretch. Because what were doing is, because we went
down in the overall section width of your tire but we went up in aspect ratio, you’re
essentially doing pluses and minuses overall to get to what stage stretch you’re doing. So you might want to redo that all over again,
you can watch it over but trust me it’s completely worth it because since you’re going down in
sections of ten that gives you one stage of stretch. If you go down five in terms of your width
your aspect ratio of your tire that is also one stage of stretch. I don’t know why I’m doing so much with my
hands but it helps me articulate what I’m trying to say. And remember that this math works backswords
as well, so if you have a two fifty five thirty five on a ten wad and you wanna go slightly
meatier than just the straight up and down look you can go up to a two sixty five thirty
five for what we will call a stage one meaty look. We don’t really have a better name for it
and the more I say meaty the weirder it sounds, but it goes for the same way. Two fifty five forty would also give you a
stage one “meaty” look. Now we described a two thirty five thirty
five and a two twenty five forty as a stage two stretch and you’re like how does that
work? Well the reason that that works out to be
the same size of stretch is because of how the aspect ratio works with your section width,
meaning that because you have more side wall on that forty series that it’s gonna bend
in just as much as a wider wheel would with less of an aspect ratio on the side. So trust me now this isn’t exact math, but
this is gonna get you as close as you could possibly get to calculating out your stretch
and we’re gonna put some pictures during this video so you can kinda see what it looks like. Now if you wanna go out and actually just
see what a two thirty five twenty five eighteen looks like on a ten wide wheel, you can go
out to our gallery and enter in that tire information and you’ll
be able to see exactly what it looks like on thousands of vehicles. That’s the whole reason that we have the gallery. It’s why we want you to add to the gallery
so that we can get other people the fitment that they want. Now one very important thing to remember is
that if you choose to use your aspect ratio, your side wall, as how you’re going to stretch
up or stretch down your tire, you have to remember that the higher number you go like
a forty versus a thirty five the wheel will sit taller than a thirty five side wall and
that just has to do with the fact of your inflation and a couple other things. So if you’re looking to make sure you can
get as close as you possibly can to the ground or maybe you’re trying to get that perfect
thunderlook you will want to use the overall section width, that would be the actual width
of your tire as your “stretch stages” instead of your side wall. Now you can do both but again we don’t recommend
going past three stages of stretching. – [Alex] He’s probably actually like working. Now we’re gonna add one more level of confusion
because in case you weren’t confused yet my goal is son of a [Bleep]. So in case that hasn’t been confusing enough
we have another level of complication to add to this. Now you remember if you go down ten in your
section width you essentially get one stage of stretch. Or if you go down five in your aspect ratio
you’ll also go down in one size of stretch. Now you can also attribute that to the width
of your wheels, meaning that if you had a two fifty five thirty five on a 18X10, which
is our square set up, remember that’s our baseline. And we choose to go up to a ten and a half
versus a ten, we now have also accomplished one level of stretch. Every half inch of width of your wheel is
also going to be another variable that can essentially go to one stage of stretch or
one stage of meatiness depending on which way you go. So you have three different things that can
essentially attribute to the stretch look of your tire. So a couple great baselines for I would say
a stage zero is going to be your 18X9 two twenty five forty and an 18X9 two thirty five
thirty five. So remember that’s gonna give you that nice
up and down look which actually looks pretty good on a lot of sport hatches and BRZ FRS’. It’s gonna be a great starting point. Now if you’re looking to get into the math
you can use some of those numbers I just said to start your baseline. Now stage one is what we call a mild stretch,
meaning that it’s what you’re gonna get away with if the police actually care about your
stretch tires. It’s gonna be something you’re gonna be able
to get away with with a little bit of a sportier look but still be able to tuck your wheel
inside your fender if you’re getting really close to that fender and you decide to roll
it. So we’re gonna give you a couple numbers on
what we would call a “stage one” stretch. Some examples of those numbers include and
18X10 two forty five thirty five and a 17X11 two fifty five forty. If you go up to a stage two we’ll call that
“max stretch” or solid stretch depending on how crazy you decide you want to be. But a stage two stretch is where you’re gonna
start to see that tire pull away from the wheel. You’re gonna start to see the lip of the wheel. And of course we’re gonna give you that disclaimer
again if you stretch your tires you risk debeading, all that lawyer stuff, we’re not liable if
anything happens or if your tire blows up and blah Stage two is gonna be taking that
another step further and that’s what a lot of people, we would say ninety percent of
the people want when we say they want a “stretched set up”. Especially in our emails. Most are talking about a stage two stretch. You will see a lot of people that run a stage
two stretch do have curb rash and it has a lot to do with the fact that people don’t
think that they ever curb their wheels until they realize that they pull their tire away
and they run into things a lot more common than they think. So just take that into con if you choose to
do a stage two stretch. You’re risking a lot but if you risk it for
the biscuit and that’s what you want we’ll give you some examples of tire set ups that
are stage two. Two examples of that include and 18X12 two
eighty five thirty and a 15X9 one ninety five forty five. So you can use those two numbers as examples
for your stage two stretch and then attribute to what your set up is going to be and that
will give you what stage stretch you want. And finally we have what we would call a stage
three stretch. Now this is about as extreme as you get. We are not liable. We are not responsible. We are not gonna tell you that you should
do this. We’re not anything of that. But if you wanna know what the maximum stretches
for what a lot of people do in the scene that we do not condone because we are a business
and we are not liable for that sort of stuff. This is what it sits at. Some examples of a stage three stretch what
we call a full stretch would be an 18X10.5 two twenty five forty, a 19X14 three fifteen
thirty a 16X11 two twenty five forty five. Now for stage four set ups you are absolutely
not going to want to do that ever so we’re not even gonna talk about it. Don’t do it. Just don’t. Don’t do it. And then obviously since we go back into an
18X10 two fifty five thirty five let’s just go into a meaty set up and that’s going to
be the exact opposite way. That means that your tire is bulging out farther. It’s gonna give you a heavier track set up. It’s gonna give you more traction path. It is going to give you just a stronger connection
to the ground. And it is what I would recommend you do if
you’re looking to do a track oriented set up. Remember you can do camber on track oriented
set ups. You wanna be probably under negative three
degrees though if you look to tuck your meaty set up underneath your stock fender. What we do say is anything above a stage two
for a meaty set up though you are going to lose a lot of the attributes that make a wider
tire better. You’re gonna have loss of traction due to
the fact that you’re not gonna have the same connection points as you would on a properly
set up tire. Now if you go into the real math of it it
can be an entire mess but what you do need to know going up a size, or going up two sizes
is probably all that we would recommend if you’re looking to do a meaty set up. So this is one of those videos that is a little
bit more moderately math oriented it is gonna require you guys to watch two or three times
if you’re trying to do your own math but we will put a little bit of a formula in the
description below. If you’re interested in seeing what these
tire set ups look like with an actual picture, check out our gallery at You can actually enter in the tire size and
wheel size of what you’re looking to buy. There are cars in our gallery that have that
exact setup. So you can see what those tire stretch or
meat set ups look like. And of course if you’re looking to, you can
add to our gallery if you have an app to mark your car, If you’re looking for wheels and tires and
you’re looking to get that stretch set up or that meaty set up you can just get a square
set up like ninety percent of the world, you can go up to and you
can build your own package. We have thirty thousand wheels, tires, all
that sort of good stuff. Everything from your gram lights to your volks
to your ESRs to your and I mean everything absolutely everything. Don’t forget to subscribe. I’m Alex from Fitment Industries. Thank you again to H3LLK1T3 for providing
us this math. It was absolutely awesome and we will see
you later. Peace.

Only registered users can comment.

  1. If you guys need help on some tire setups, check out our gallery! We have thousands of different matchups in there!

  2. I would need a confirmation from you : when you calculate your stretch stages, I assume you always start your calculations with a 35 thickness tire ? In case this isn’t clear I’ll give an exemple if you reply 👍🏻

  3. i want to buy rohana rfx11~
    20*10 fronts 20*11 rears for new ecoboost mustang.
    what tire size you suggest ?

  4. Hello I have a question I have one
     18 inch wheels
    I have instead of
     245 40 18 I just set up a little narrower two 225 40 18 there
    that is for the front tires and rear tires I have put 255 40 18 normal’s 265 35 18 is the narrowing tire would be a problem for me.
    car is Mersedes E clas

  5. Please help! I’m not holding you liable. But can I run a 245/35 on a 10.5 wide wheel? Is that a “stage 2” stretch? Thanks!

  6. In Bulgaria we have moon craters, and if you try to drive around whit these your tires are not gonna last for a long. But anyways i will try it 😁

  7. I like how you make a very intelligent sales pitch in order to get your business. Point is that you're exploiting the young, uneducated, not well off class of people. Shame on you. Its a tire. Circle. Made to go round and round, that's it. You guts are making into a material object.and most important you're making our highways more unsafe than ever. Think about the other guy and the guy who has to follow a blown out tire due to inadequate camber. Hope you have good insurance. It's going to happen.. Just when???

  8. THIS CONFUSINGGG. I need your guys' help. I'm good at math, but gosh this is hard. I have 18×8. If it helps I got MB battles, & there 18×8, but I don't know which tires to get! I'm going to be tucked(it on air) so which will be right tires to run! Pls, help me 🙁

  9. So OEM Specs say 275/35 on my rears (18×9.5) which would be considered a stage 3 meaty set up correct? So should I just run 265/35’s instead?

  10. I found a website that will calculate stretch for you with out doing the math

  11. Hello What will you recommend for a 18×9.5 +38 Mst wheels on stock suspension, currently running 245/40/18? 2018 Subaru Wrx

  12. So going by the example listed "195/45 on 15×9= stage 2 stretch" my setup of 195/50 on 15×9.5 should also be stage 2, right?

  13. Is it safe to run different profile tyres on a staggered 18inch setup wheels?.. currently running front 9.5 width with 225/45 and rear 10.5 with 245/45 on a mitsubishi lancer gt.. Plan to change the rear to 235/40 or 245/40 at the rear and maintaining the front..

  14. I have 15×10 wheels wat tires can i get to have a stage 1 strech and keep a decent side wall on my tires

  15. Would I be able to run a 265/70 (stock 06 Silverado 1500) on a 17×8 (the stock rim is 17/7) so the stretch shouldn’t be that big of a difference right?

  16. I just bought a set of 265/40R19 tires for a set of 19×10 wheels. It's roughly 1/2" stretch over the recommended 9.5" wheel. I assume this should be OK?

  17. Who can give the best results
    A typical av sedan car with coilovers, 20 inch 7.5?

  18. Can you stop speaking american and start speaking like humans ? You know the whole world uses metric right ?

  19. If anyone need any help i gotchu, first start with the square setup, 255/35 on a 10" wide. Now if you are getting a different width wheel, you calculate that first. 225/35 on 10 wide is zero, but if ya smack that same tire on a 8 wide you have stg 4 meat. Then you zero it out. Once you do that you just mess around with the aspect ratio and cross section to achieve what you want.

  20. Hey Alex love the videos from FI. Keep it up, do u mind doing a video based on all those numbers eg 18×10.5 – noob to the rims game

  21. What are the stretches with 225/45 tires with 18×10.5 rims and same goes for the rear but its 245/45 tires with 18×10.5 rims

  22. Hello. Very confusing lol. But i own a 2000 GS 300 Lexus and i bought the 2013-2014 GS350 F sport type rims 19×8 and 19×9 with offset of 45 and 60. I want to get tire size 235/40/19 F and 255/40/19 R, would that work out?

  23. Pulling my brain out here about what tyre to get for my 18×9.5+35 wheel.

    Was thinking

    245/35/18 OR 255/35/18

    Or even 245/45/18

    I actually used to have 17×9+42 wheels with 235/40/17 but I didn’t like the stretch it gave so I went with a 245/40/17

    I am on BC coilovers and rolled fenders.

    I don’t want a complete track look car but again don’t want a too silly stretch.

    Any tips

  24. I need some help! I have a BMW Z4. I got 18 inch wheels staggered. The rear are 9 and the front are 8,5… I want a middle stretch. I don't want to meaty, but I don't want either a skateboard wheels looking… I was thinking in use 205/40 on the 8,5 and 215/40 on the 9 … but I still not sure….

  25. i want to get federal 595 rs-r for my 18×10 work vs xx do you guys recommend a size for the federals i want the stretch similar at 3:32. please whoever see's this pls respond

  26. If we go down in diameter (meaning higher ratio in the process) and width from the example, the formula starts to get a lot worse. Already in the example the width of the wheel has the largest effect. Half an inch is more than 10 mm so it's quite obvious. Ratio has by FAR the smallest effect and it stays smallest even in extremely low profile tires that don't even exist. Also, with ratio alone you can't even accomplish a stretch to begin with.

  27. Soooooo…….you're not going to stretch my tires when you mount them and send them too me!?!? Lol 🤣
    Just kidding, stretch is stupid….I WANT MEATY!!!!

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