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Old 12-02-2014, 06:43 PM   #1
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Tire size

I just recently purchased a 2008 SMB that had 245/70 r17 tires on it and want to put something larger on it as the tires look a little under sized. I'm considering 305/65 r17 tires. Does any body have this size tire on theirs and if so, do you have any problems with the tires rubbing or hitting? I'm getting an Aluminess front bumper so I'm thinking behind the front tires should be the only problem if there is one.

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Old 12-02-2014, 09:17 PM   #2
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Re: Tire size

I went with 285 75 R16 and are quite happy. I believe this is also SMB standard size.
I still get a bit of rubbing inside the tire
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Old 12-03-2014, 01:39 PM   #3
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Re: Tire size

Go with 265/70 17 and save your self all the trial and error others have gone through. Quigley conversions will rub with 305's. Taller is better than wider.

If you have 410 gearing or taller, don't go over 285's.
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Old 12-03-2014, 04:12 PM   #4
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Re: Tire size

Quote:
Originally Posted by j.whitbread
Go with 265/70 17 and save your self all the trial and error others have gone through. Quigley conversions will rub with 305's. Taller is better than wider.

If you have 410 gearing or taller, don't go over 285's.
Lots of folks have run 305s or bigger with 410s on their SMBs. The OP doesn't mention whether he has 4WD and a lift or not but I have 410 gearing with 315s and no issues except for a slight rub at full articulation.

But if I do I look forward to it so I have an excuse to buy a full floater
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Old 12-06-2014, 12:49 PM   #5
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Re: Tire size

Quote:
Originally Posted by j.whitbread
If you have 410 gearing or taller, don't go over 285's.
I'm still curious about this statement without more context. Doesn't it have more to do with type of axel? Are 35s too much for a limited slip differential in a semi-float? Maybe 4.56 but I don't want to give up the mpg any more than I have to.

Thinking of putting a full floater on and upgrading the brakes from something bigger than what I have now.
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Old 12-07-2014, 09:37 AM   #6
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Re: Tire size

Generally speaking whatever the sizes, too tall can make the van search for gears, get lower mileage because it's working too hard at cruising speed, etc.
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Old 12-07-2014, 10:48 AM   #7
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Re: Tire size

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Originally Posted by j.whitbread
Generally speaking whatever the sizes, too tall can make the van search for gears, get lower mileage because it's working too hard at cruising speed, etc.
OK, I get it. I thought you were referring to wear and tear on the drivetrain. That is, in my case, 35" tires with 4.10 gearing might be too much for a semi-float rear axel.

I don't notice gear hunting on long grades but maybe that's because of the custom PCM/TCM tune I had written for my 6.0 psd.

I guess I could go lower and have longer legs for the freeway (ie., lower rpms and better mileage) but I would sacrifice torque and towing capacity? That just seemed like a blanket statement to not go over 285s with 4.1 gearing. Lots of folks are running 305s and 315s. Just curious.
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Old 12-07-2014, 11:34 AM   #8
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Re: Tire size

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Originally Posted by JoeH
Quote:
Originally Posted by j.whitbread
Generally speaking whatever the sizes, too tall can make the van search for gears, get lower mileage because it's working too hard at cruising speed, etc.
OK, I get it. I thought you were referring to wear and tear on the drivetrain. That is, in my case, 35" tires with 4.10 gearing might be too much for a semi-float rear axel.

I don't notice gear hunting on long grades but maybe that's because of the custom PCM/TCM tune I had written for my 6.0 psd.

I guess I could go lower and have longer legs for the freeway (ie., lower rpms and better mileage) but I would sacrifice torque and towing capacity? That just seemed like a blanket statement to not go over 285s with 4.1 gearing. Lots of folks are running 305s and 315s. Just curious.
Lower rpm does not necessarily mean better mileage if the engine is working harder to go that speed.
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Old 12-08-2014, 09:31 PM   #9
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Re: Tire size

I made a mistake and bought a brand new set of 285's for my stock SMB lift then added Deaver springs. After that the van looked like a tall guy with short legs. Sold the 285's for next to nothing then added 315's which looked great but made getting into the van difficult. So I added different steps... more money. The 315's did attack my bushwhackers with the sway bar disconnected during heavy articulation. Had to fix that. Turned into one of those "do this to fix that, and fix that by doing this & fix this to fix that" kind of things.

I was totally surprised how much better the 315's (MT Toyo's) drove compared to the same tire in 285, although the 285's cornered slightly better. Kept the same 16 wheels though. I'd love to have 17's so I could go to a better braking system but would have to replace 8 tires and wheels... more money.

Drive wise, I didn't notice much difference at all with shifting going from the 285's to the 315's. Last month I did install a SCT tow tune. Seems a bit better now but again not a huge difference.
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Old 12-20-2014, 06:59 PM   #10
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Re: Tire size

Anyone have experience stepping up a tire size from 245/75/R16 with 3.55 gearing?

I have a quigley 4x4 5.4 v8 with 3.55 gears and 245/75/r16 tires now

I'm wanting to go up to 285/75/R16

I do have BAJASPORTSMOBILE rid improvement package up front, so I'm 2" taller than a stock quigley, 6" taller than a 2wd factory econoline.....

Will this new tire size be too much for 3.55 gears? I do hear of occasional rear wheel well rubbing on quigleys with 285/75/r16.... Not too worried about that aspect.....

Expertise please!
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