I can't decide 30x9.5 or 31x10.5?!?!?!

The way i see it it basically comes down to a personal preference. Some people are more willing to try stuffing big tires in their wheel wells then others. I'll explain my situation and i'd love it if people would weigh in with their experiences and opinions.

My current set up is a 4 door Vitara, jeff's lift, 5.13's, rear locker, 15x7 steelies and 1.25" spacers, 215/75's.

2" body lift is on the way so i can get some real tires underneath my Zuk, i just need to decide which size. On a side note, i tow my 14.5ft whaler with my Vitara so gearing is a factor.

My main concerns is clearance in the wheel wells. Before i had my 215's i had 235's and with just Jeff's lift they didn't fit very well. I trimmed as much as i was willing to and they still rubbed really bad off road. Finally i gave up and traded them in for the 215's.

I want bigger tires, but i don't want my tire's to rub. Articulation vs. ground clearance. 30's vs. 31's....

Any opinions would be greatly appreciated, i'm totally lost on this one 

Thanks for the input and your right; gearing is a big factor.

The Vitara has proved a great tow vehicle. Granted my boat isnt very heavy, maybe around 1000lbs.

I didn't like the power loss with the 235's (29") and stock gearing. Going down to the 215's (28") gave me a better ratio and towed just fine. Then I swapped in the 5.13's and now it's overgeared and to be honest I love it. 5th gear is my new best friend!   

I'm ready to loose a bit of power. Going to 30's would equate to roughly stock gearing and 31's would mean under geared, again.

I guess there are a lot of pros going with 30's. They'll almost certainly fit (no trimming) and I'll maintain a good gear ratio. The only con is offroad-ability.

Anyone else have any thoughts??

By 'bigger' do you actually mean taller AND wider... or do you really just want a 'taller' tire?  The rubbing you had, was it interference from the Vitara body cladding and trim?  Have you considered going with 16" rims and running 215/85/16" tires (30+/-") or 235/85/16 tires (30.7") tires?  

These are both 'taller' tires but the 235/85/16 would have the same cross section width as the 235/75/15.  The 215/85/16 would be 20mm narrower in the cross section (almost an inch narrower).

As far as power, my gear calculator reflects 5.13s are well suited for 30" diameter tires with a slight increase over stock mechanical advantage (jumping up from my stock 4.62 gearing I had in my Tracker) and would and could pull a 30.+" tire with a slight loss of mechanical advantage over stock gearing.  Taller and wider tires are heavier and present more clearance issues with the top of the rear fenders, especially when you have spacers pushing your rims further out from the hubs and will require more 'power' to turnover when driving.  The extra weight in larger/wider tires is a big 'power' draw and impacts MPG significantly because of increased rolling resistance.

So I'm thinking going wider and taller represents more potential issues and going just taller less issues to deal with.

in hind sight i kind of wish i'd stuck with 16's. not because of the wheel spacers that are required with 15's but because of the narrower tire options.

A 31x9.5 or even a 30x8.5 would be awesome, but unfortunately such tires do not exist for 15" rims. Anyways, the fact is i paid a pretty penny for my 15" steelies and i'm not likely to go back to 16's now. 

The more i think about it the more 30x9.5's make sense. I guess i may have always known that but i was hoping someone on here would talk me into 31's 

I may not be the most knowledgeable, or practical, but I'd say go with 31s...

I've got 245/75/16s on my rig with Jeff's lift... with minimal rubbing off road.  In the spring if I do a 2" body lift, I'm going to try and stuff some 265/75/16s on it... 

I'm running a beefy AT 245/75/16, which is a heavy ass E ply...

I have something simular to Jeff's lift, essentially spacers, and clear them just fine

problem is... they're heavy and the added size is noticable obviously from stock and unlike you, I haven't touched my R&P

Its a good size for wheeling for sure, but wish it came in a C ply... as I don't need its 4000lb weight capacity per tire for our little trucklet

|removethispart|@ the end of the day, and I know this may be faux pas to say...

I haven't found a huge difference in my wheeling capability from going from a 235/75/15 BFG AT to the lift and the 245/75/16, other than power loss

the look on the other hand is more substantial!

I run a 1.6L Tracker so it is different for you, but knowing what I know now, I would never have gone to the 31's!! The power loss and fuel economy loss over the 30X9.50's is HUGE and as someone else mentioned, the off-roading ability isn't noticeable at all (except the riding the clutch constantly!!). Sure the 31's look awesome, but once they're worn out..................30's it is!!

I'd vote the smaller size.  I went from 205/75/15 stock tires to 215/75/15 BFG AT's and that was a noticeable power and fuel economy loss.  I have 4.62 gears though.

I have a 1990 Suzuki Sidekick with a 1.6. I have 30x9.5 on a 15" rim. It's great on the hwy and off road. To go to 31 and only get a 1/2 inch more, power loss plus gas and wear on clutch ext, ext  is not worth it. Put your money into skid plates rocker pannels and ARB lockers and you can go anywhere.

just my thoughts

Thanks for all the input people!

If this was a vote i think 30's would be winning (so far at least).

I tend to agree with everything thats been said. It's pretty disapointing that even with a suspension and body lift these little trucks still struggle to fit 31's in the wheel wells. Power loss is a whole other issue...

But really when it comes to offroading is a 1/2" of ground clearance really going to make a difference? I don't think i'll hear my spotter saying a can't make it over that rock because i chose 30's over 31's. 

I have a 1990 Suzuki Sidekick with a 1.6. I have 30x9.5 on a 15" rim. It's great on the hwy and off road. To go to 31 and only get a 1/2 inch more, power loss plus gas and wear on clutch ext, ext  is not worth it. Put your money into skid plates rocker pannels and ARB lockers and you can go anywhere.

just my thoughts

Same here
I have went plenty of places with 30X9.50X15's, rock sliders, skid plates, and ARB's.

I know this sounds really stupid but for me the evil one inch difference is a big one. In my mind there is a big divide between 30's and 31's.

31's are officially a 4x tire. They round out the bottom end of offroaders tire spectrum, but at least they're on there.

30's on the other hand, are small and kinda meant for 65 year old's in Florida... (no offence)

or maybe i'm just crazy 

Most "30"s are not even close to being "30"s.  Case in point: BFG A/Ts in 235/75/15s are just barely shorter than the 30X9.50X15 BFG A/Ts.  In fact, I'd argue they are closer to a 29" tire than an actual 30" tire and 235s are closer to a 28" tire than a 29" tire, especially after they have 10K of road wear on them.

It's all in what you want, what you want to do, and what you're willing to accept in any trade offs.  Pick one and go for it.  You know (and I know... and most the guys on here reading this know) this isn't going to be the end of the mods you do with your truck anyway.  It is just the next thing you are contemplating to do to your truck.  You only live on this earth once.  Get some.

It's all in what you want, what you want to do, and what you're willing to accept in any trade offs.  Pick one and go for it.  You know (and I know... and most the guys on here reading this know) this isn't going to be the end of the mods you do with your truck anyway.  It is just the next thing you are contemplating to do to your truck.  You only live on this earth once.  Get some.

Amen