What psi are you running your 285/50r20's. Ride Stiffness?

[mrezo]

I just picked up a set of Nitto Terra Grappler G2's this past weekend.
I noticed that the LR4 tracks much better on the highway but there is now some added stiffness in the ride quality. Assuming that the shop inflated the tires too high.

Curious to know what other members with this tire size setup are running?

 

[Jomcool]

Regardless of size, I try to run the tire pressures at the factory specs unless off-roading where I drop the pressure a good bit. My LR4 seems to drive well on road at the factory specs listed on the door jam placard. I believe it is 42 in the rear and 36 in the front.

 

[mrezo]

Thanks @Jomcool. This was my thinking exactly. Just wanted to double check as I’ve read of others who’ve maintained the same pressure all around after making the switch to A/T tires.

I’ll double check the pressures this weekend and report back on ride quality.

 

[umbertob]

Generally you always stick to the recommended factory pressure shown on the driver's door tag, as long as your P tires are XL (Extra Load) range, which is what Land Rover recommends for the LR4, regardless of rim or tire size. If you switch to LT (Light Truck) tires with an "E" Load Range - such as my 18" Nitto Terra G2s - then you need to inflate them more to compensate for the much higher maximum load pressure rating and stiffer sidewall of those tires.

A quick check of Nitto's web site suggests your size tires are P-metric, XL range. You should stick to the PSI recommendation by Land Rover, and possibly even a few PSIs less if you don't normally carry a full load.

 

[Julian Liu]

Hi mrezo,
Did you get those Nitto's from me? I don't recall what pressure I put in them, I like stiff ride, so I likely got them 4-6 psi above the LR4 recommended setting if that didn't exceed the tire max rating. For the BFG AT, I put 44 front and 50 rear, but I think those tires have max pressure of 80 psi. I air down to 20-25 psi off-road.

I didn't know your spare is19". I have a set of (5) OEM 20" wheels for sale

-Julian

 

[mrezo]

Hey @Julian Liu,

Yes! I did grab them from you. Small world.

I ended up buying a full size spare from a NorCal LR member and fitted a new G2 on it.

The tire does make contact at full lock and makes a noticeable rubbing sound on the driver side. I’ve routed the exposed wiring loom up higher onto the frame.

The interior ride is noticeably stiffer where I can now feel every bump on the road and cabin noise is much louder. (Even the wife mentioned it to me and she never notices stuff). Ride quality is definitely not the same as it was before the swap. Theres some harmonic vibration through the steering wheel at highway speeds depending on the smoothness of the pavement.

I mounted the tires with the new design pattern on the sidewalls exposed. Perhaps this is causing some of the issues as you may have mounted the tires with the original sidewall design face out?

 

[ktm525]

For "stock" sizes I run 34-36 psi front and 36-38 rear. The 42 psi rear rec. by LR assumes full carrying capacity (cargo and/or trailer tongue weight). If I run 42 rear then I get accelerated wear in the center of the tire versus the edges which suggests over inflation for light loads. 36-38 rear is perfect for light loads.

 

[Jomcool]

Yes, good comments on the XL load range and also on the load carrying capacity at higher pressures. I always run the advertised pressures on-road because you never know when you'll end up with a load of seven fatties inside and/or a trailer attached where I live. I just rotate regularly to manage the potential wear.

 

[Julian Liu]

Hi mrezo,

I didn't have the Nitto's on the truck for long, so didn't pay attention to which sidewall was on the outside and didn't notice the rubbing sound. My wheels are 20"x8.5" double spoke wheel, maybe different width or offset than yours? The louder interior noise and rougher ride could be due to switching from "street" tires to all terrain tires.

 

[mrezo]

First, I just want to say how great the community members of this forum are. Two thumbs way up to all that have chimed in!

@umbertob , thanks for the detail and for also double checking the tire load.

I checked the tire pressure and as suspected, the tire shop inflated all tires above spec. They were at 46 psi all around which would explain the elevated harshness to the ride.

I took @umbertob 's and @ktm525 's tips and lowered the pressure to a tad below spec and the ride is now back to what I remember the LR4 riding like.

@Julian Liu, I agree that making the switch to AT definitely attributed to the rougher ride and in cabin noise. I'm not sure what my offset is but it could be different as I do have some rubbing when the wheel is at full lock when turned to the right. I'm pretty happy with the ride quality now that I've got the air pressure dialed in and in cabin noise is definitely acceptable.