Tire fitment question-- need help before I purchase

JakeJK · Feb 26, 2016

Okay so I've been looking into tires and am planning on buying within the week. I want to make sure I'm not buying a size that won't fit on my jeep.

Specs- 2 door on 2.5 inch RK stock mod(netted 3 inches front and rear)
Spidertrax 1.5 inch spacers
XD bomb 18x9 with 5 inches of backspace.
So I'll have 3.5 inches of backspace with 3 inches of lift

Can I fit 315/70r18(35.36x12.4) Toyo MTs on it Without having to cut anything out?
Reason I ask is because they're cheaper but bigger than 35x12.50 and It dosen't make sense for me to buy smaller and more expensive

Thanks!

wayoflife · Feb 26, 2016

JakeJK said:
Can I fit 315/70r18(35.36x12.4) Toyo MTs on it Without having to cut anything out?

So you know, MOST advertised 37x12.50 (what is written on the sidewall) tires will have a true measurement of about 35". Most 35x12.50 tires will have a true measurement of about 33". While you certainly can make an advertised 37" tire work with just 2.5" to 3" of lift, you will need to cut your fenders and pinch seam and probably a bit more here and there to make it work. You will also want to make sure you have the proper bump stops installed and they should be about as tall as you have lift.

JakeJK · Feb 26, 2016

wayoflife said:
So you know, MOST advertised 37x12.50 (what is written on the sidewall) tires will have a true measurement of about 35". Most 35x12.50 tires will have a true measurement of about 33". While you certainly can make an advertised 37" tire work with just 2.5" to 3" of lift, you will need to cut your fenders and pinch seam and probably a bit more here and there to make it work. You will also want to make sure you have the proper bump stops installed and they should be about as tall as you have lift.

Okay, I remember you saying that about the Standard measurement tires, wasn't sure if there was any play with the metric tires or not. So the 315s will measure more like a standard sized 37?
How do you think 305/70r18s would fit (34.8x12.01)?

wayoflife · Feb 26, 2016

JakeJK said:
Okay, I remember you saying that about the Standard measurement tires, wasn't sure if there was any play with the metric tires or not. So the 315s will measure more like a standard sized 37?

"Most" 315's measure up like a standard 37. The ones you posted up definitely do.

How do you think 305/70r18s would fit (34.8x12.01)?

This will still be a really tall 35 or a really short 37.

JakeJK · Feb 26, 2016

wayoflife said:
"Most" 315's measure up like a standard 37. The ones you posted up definitely do.

This will still be a really tall 35 or a really short 37.

I see now on TOYOS website the inflated tire height and width, should I shoot for something that measure 33-34 inflated? The 285/75r18 I think was like 35 which would still be big

wayoflife · Feb 26, 2016

JakeJK said:
I see now on TOYOS website the inflated tire height and width, should I shoot for something that measure 33-34 inflated? The 285/75r18 I think was like 35 which would still be big

You should understand that the 285 or 305 is the tread width in mm. The 70 or 75 is the percent of the tread width and that makes up the sidewall height. So, even though you're getting a narrower tread with a 285, you are still getting 5% more sidewall height out of the tire.

If it were me, I would go with the 305 and make it work. Sure, you'll have to address some rubbing but it should be too much and I think they'll look good. 315 is just a bit too big for what you've said you're wanting.

JakeJK · Feb 26, 2016

wayoflife said:
You should understand that the 285 or 305 is the tread width in mm. The 70 or 75 is the percent of the tread width and that makes up the sidewall height. So, even though you're getting a narrower tread with a 285, you are still getting 5% more sidewall height out of the tire.

If it were me, I would go with the 305 and make it work. Sure, you'll have to address some rubbing but it should be too much and I think they'll look good. 315 is just a bit too big for what you've said you're wanting.

Yeah I know, I did the calculations to figure out the standard number I put in parenthesis, I think I will go with the 305s I think I'll be able to handle the rubbing issues like you said

Thanks for the help

Clifford33 · Feb 26, 2016

So Eddie I have a 16 inch wheels should I get 315s or get 17s and do 35s if I'm wanting the Heights of a 35?

Tire fitment question-- need help before I purchase

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