Bigger tires- how to improve ride?

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offroad_path
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Bigger tires- how to improve ride?

Postby offroad_path » Mon Mar 20, 2017 12:44 pm

Hoping to get the wisdom of others here. Since this is ride related I posted it in suspension.

I got a 2008 LE V8, came with 265/60R18 tires stock.
I have since switched to Bf Goodrich AT KO2, but at 285/65R18. So a reasonably bigger and heavier tire.
I primarily did this because I really like the look and it fills out the wheel wells perfectly. However a side effect has been the ride, which was never great to start with, has got worse.
I am running Bilstein 4600 front and back.

My biggest issue, besides the rough ride, is the wobble when hitting bumps - especially with just one side of the car. I wouldn't call it a death wobble, but the steering wheel vibrates enough to get seriously annoying. Occasionally the back will jump around.

I have:
1. Had all suspension components check. The shocks only have 5000 miles on them
2. Had alignment done by a repeatable shop with experience with 4wd alignment
3. Had everything checked by multiple shops for anything lose / broken / missing / just plain stupid.
4. Run air pressures from 30PSI up to 45PSI (pressure recommended by BFG for this tire on this truck). 30PSI did help, but tire wear was just too high to continue at the pressure.

All I keep getting back is that the tires are causing the problem. I get that bigger tires are going to make things worse.

My question is, what can I do to compensate for bigger tires?
a. Stiffer shocks? Seems that would make it worse.
b. Softer shocks? I don't know if i really want to start bottoming out all over the place
c. Better springs? Pretty sure the current ones are stock or stock replacements
d. Stronger components elsewhere?

Any suggestion would be greatly appreciated. Any of these changes aren't cheap so I am hoping to get as much info as possible before I proceed.

Thanks in advance.


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Thupertrooper
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Postby Thupertrooper » Mon Mar 20, 2017 4:45 pm

Really common on our trucks has to do with the rack and pinion setup with big tires.

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smj999smj
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Postby smj999smj » Mon Mar 20, 2017 9:32 pm

The ride in these trucks are pretty sensitive to tire choice. If you want a good ride, you don't go with the choice you made. Best riding tires I've experienced in an R51 was on Michelin LTX M/S2 tires, which are now being replaced by the Defender LTX M/S model. These are highway all-season tires, so they will not have the aggressive look of the KO2's you were looking for.
As far as tire pressure, I would stick with 35 PSI (cold) as recommended by the vehicle manufacturer. The 4600's are a good choice for shocks and having the alignment done is good. Airlift 1000 air bags in the rear help and switching to a 17" wheel is probably not something you want to hear.

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offroad_path
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Postby offroad_path » Tue Mar 21, 2017 10:56 am

Thanks guys for the responses.
All very useful info.

@smj999smj I do do a fair bit off off roading so an all season wasn't ideal for me. That being said the LTX is a great tire I had on my 4Runner, so a very valid suggestion.

@Thupertrooper Very interesting info, thank you.

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Postby peterpeterson » Tue Mar 21, 2017 11:13 am

smj999smj wrote:The ride in these trucks are pretty sensitive to tire choice. If you want a good ride, you don't go with the choice you made. Best riding tires I've experienced in an R51 was on Michelin LTX M/S2 tires, which are now being replaced by the Defender LTX M/S model. These are highway all-season tires, so they will not have the aggressive look of the KO2's you were looking for.
As far as tire pressure, I would stick with 35 PSI (cold) as recommended by the vehicle manufacturer. The 4600's are a good choice for shocks and having the alignment done is good. Airlift 1000 air bags in the rear help and switching to a 17" wheel is probably not something you want to hear.
Why would switching to a 17" wheel improve the ride? More sidewall cushion? I wouldn't expect it to help with those rock solid BFG KO2 sidewalls...

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smj999smj
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Postby smj999smj » Tue Mar 21, 2017 6:48 pm

Going to a smaller diameter wheel (overall tire diameters being the same) means more air volume and better cushioning.

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Re: Bigger tires- how to improve ride?

Postby kevinthefro » Thu Mar 30, 2017 11:13 am

offroad_path wrote:the steering wheel vibrates enough to get seriously annoying. Occasionally the back will jump around.
My car behaves precisely the same way. I put in a 2" lift and KOs and it handled fine, then after two years with no changes it started getting wobbly so I don't buy the theory that tires or lift are the cause.
I think it's bushings or ball joints. I'm replacing control arms one at a time until I'm proven wrong or behaves like it did three years ago.

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NVSteve
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Postby NVSteve » Thu Mar 30, 2017 1:09 pm

smj999smj wrote:Going to a smaller diameter wheel (overall tire diameters being the same) means more air volume and better cushioning.
I would have suggested a 16" wheel. Still blows my mind that people are happy driving around on 20"+ wheels.

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offroad_path
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Postby offroad_path » Thu Mar 30, 2017 2:28 pm

I get the point, and that makes sense.
What I don't get though is technically I am running more air than the stock as I am on 285/65 tires.
smj999smj wrote:Going to a smaller diameter wheel (overall tire diameters being the same) means more air volume and better cushioning.

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NVSteve
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Postby NVSteve » Thu Mar 30, 2017 3:15 pm

offroad_path wrote:I get the point, and that makes sense.
What I don't get though is technically I am running more air than the stock as I am on 285/65 tires.

I'm guessing those new 285s you are running are LT tires? And by "more air," are you talking strictly PSI? LTs can take a butt load more PSI over P-rated tires, so they can take "more air." But the more air, the firmer the ride. I run my LT 265/75/16s with about 40psi. Firmer springs will only make the overall ride firmer. I have felt mine jump around since day one, especially while making a curve with a large crack/bump in the road. First thing I did was replace the stock suspension, which kept bottoming out on me, with firmer springs and new shocks. No more bottoming out, but it will still hop around on roads when hitting a crack/bump. It isn't uncontrollable, just really annoying. Having the alignment checked at a good shop would also be a good starting point.

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V8Pathy
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Postby V8Pathy » Thu Mar 30, 2017 9:15 pm

i run stock suspension 4wd 2008 v8 with 18" and bfg Ko2 275/65. They have been great the past 2 years.

35 psi cold all 4 corners.

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SETI20
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Postby SETI20 » Mon Apr 03, 2017 12:24 pm

Nice setup though. Post some pics!

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smj999smj
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Postby smj999smj » Mon Apr 03, 2017 2:10 pm

As stated, you are not increasing the volume of air so much as the air pressure. Even with tires that have the capability of holding a higher air pressure, I still would be reluctant to go over 35 PSI of air pressure on an R51 Pathfinder unless it is extremely loaded and/or towing a very heavy load. The whole reason for an "LT" tire is for increased load carrying capability and better stability under a load compared to a "P" rated tire. The compromise is ride quality and in some cases, noise.


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