235/85 vs 265/75 for daily driver

[jcush87]

235/85 vs 265/75 for daily driver; Inflation pressure

I know the 235/85 vs 265/75 argument is all over the internet and I completely understand the off-road handling aspects of the 2 sizes. I have searched and searched but have not found a decent comparison talking about the road manners on a 4runner. I have read some things about they could be squirrelly on the highway and then high aspect can cause the tire to bend sideways and provide handling uncertainty. Has anyone run both tire sizes on road? Also, I do some towing.

Looking at the BFG AT KO2s

Input appreciated!

 

[BrianSD_42]

I've run 265x75x16 (31.5") and 285x75x16 (32.9") and both are great.

Unless you have a serious lift though I would recommend sticking with the 265x75x16. AND IN A CLASS D OR LOWER.

Why?

Truck feels like it has more power.

Better MPG.

Nearly identical offroad performance for most trails.

 

[KidVermicious]

You're not driving a racecar. The slightly higher aspect ratio a 235/85 brings will have an utterly inconsequential effect next to the higher center of gravity the truck already has.

On the flip side, the skinnier tire means less rotating mass, less unsprung weight, less rolling resistance, and less air resistance. That will translate to better traction in the wet, better acceleration and stopping, better mpg, and less wear and tear on your steering and suspension components. Those differences won't be huge over a 265/75, but they won't be completely negligible either.

 

[jcush87]

Thanks for the advice, I think you are right Kid, the high aspect ratio probably won't be very noticeable.

Brian, unfortunately they don't make any C or D rated 235/85 tires that I am aware of. My wife's 4runner has E rated tires and I am aware of the harsher ride. I wish I would have done some P rated tires on hers... At least in the skinnier tires the weight rating for the load E is 3000 lbs instead of 3500lbs like the 265 width. Maybe the 235 width E will ride similar 5o the D rated 265. Heh, that's a bunch of numbers and letters for ya! I was considering the duratracs because they come in a C rating, but the reviews just aren't as good as the new BFG KO2s.

 

[KidVermicious]

Somebody told me once you only find 235 and 255 tires in E ratings because they were originally intended for DRW setups, and you don't have a DRW unless you're towing heavy and need the E rating. I don't know how accurate that is, but it sounds right.

 

[jcush87]

Well, I got em! Ended up $767.40 out the door. Not too bad considering most quotes I got were 850-950.
1996 4Runner SR5 4x4. BF Goodrich All-Terrain T/A KO2 235/85r16


They are a bit more aggressive looking than I was expecting, but I really like how they ride. The shop put them at 37psi which gave a soft ride, but felt reallt mushy and sluggish. I thought it was just from the 1" increased diameter. I pumped them up to 55psi and the truck really came back to life. I feel more bumps in the road though. What pressure do you guys run your 235/85s at?

The skinnier tires don't look bad at all to me. Can't wait to get them on some terrain that will test them!

Thanks for the help.

 

[Supermoney]

Well, I got em! Ended up $767.40 out the door. Not too bad considering most quotes I got were 850-950.
1996 4Runner SR5 4x4. BF Goodrich All-Terrain T/A KO2 235/85r16


They are a bit more aggressive looking than I was expecting, but I really like how they ride. The shop put them at 37psi which gave a soft ride, but felt reallt mushy and sluggish. I thought it was just from the 1" increased diameter. I pumped them up to 55psi and the truck really came back to life. I feel more bumps in the road though. What pressure do you guys run your 235/85s at?

The skinnier tires don't look bad at all to me. Can't wait to get them on some terrain that will test them!

Thanks for the help.

At 55 they are probably rock hard, even though I know you can fill these things up much higher than that.

My 285/75/16s are 35 lbs lol

 

[hounddogman]

Looks good . I run my 235/85R16s at 35-38 psi and they feel prety frim .

 

[Unner]

What's the load rating on these? If they are C rated then at that PSI you are pushing the max PSI if not exceeding it. On my 255/75/17's in C rating I run 39 PSI...

 

[BrandonF]

I feel like this is part of the compromise with running tires skinnier than stock. That makes sense that they feel squirmy since they have such a high aspect ratio and narrow width. All of the weight of the truck is supported by a much smaller area so you'll need to run higher psi to prevent them from feeling mushy. This will result in a harsh ride. A higher volume (wider) tire will dampen vibrations and impacts better than a skinny tire as well.

 

[KidVermicious]

They are a bit more aggressive looking than I was expecting, but I really like how they ride. The shop put them at 37psi which gave a soft ride, but felt reallt mushy and sluggish. I thought it was just from the 1" increased diameter. I pumped them up to 55psi and the truck really came back to life. I feel more bumps in the road though. What pressure do you guys run your 235/85s at?

Part of the squish is the tread blocks. They're deeper with more gap between them. If you're used to street tires or milder all terrains, the bigger blocks will feel squishy and squirmy for a bit.

I run my 255/85 load range E KM2s at about 40 PSI on the road. I think 50 or more would rattle my teeth out, but that's with mud terrains on a hurky leaf sprung 3500 lb truck, maybe it wouldn't feel so bad with your heavier ride with coilovers and links.

What's the load rating on these? If they are C rated then at that PSI you are pushing the max PSI if not exceeding it. On my 255/75/17's in C rating I run 39 PSI...

Should be load range E, I don't think you can get them in anything else.

 

[jcush87]

After I notices some tire bulge that made my tires look sort of low on air I called BFG and was told for the weight of a 4runner on these tires 55psi is what they recommend.

The tires are a load range E that are rated to support 3042 lbs at 80 psi
The same tire in 285/75 is rated to hold 3750 lbs at 80psi
So to me it makes sense that the 235\85 would require a higher psi to support the same vehicle.

As far as ride stiffness, it is firmer than the old p265/70 Michelin ltx tires but it is a slightly softer ride than my wife's 4runner with destination ATs in 31x10.5r15 in load range C.

 

[AntiVenom]

Well, I got em! Ended up $767.40 out the door. Not too bad considering most quotes I got were 850-950.
1996 4Runner SR5 4x4. BF Goodrich All-Terrain T/A KO2 235/85r16


They are a bit more aggressive looking than I was expecting, but I really like how they ride. The shop put them at 37psi which gave a soft ride, but felt reallt mushy and sluggish. I thought it was just from the 1" increased diameter. I pumped them up to 55psi and the truck really came back to life. I feel more bumps in the road though. What pressure do you guys run your 235/85s at?

The skinnier tires don't look bad at all to me. Can't wait to get them on some terrain that will test them!

Thanks for the help.

Looks good to me. Definitely considering this option for my wife´s Runner Any photos from head on?

 

[jcush87]

Head on view for AntiVenom:

 

[jcush87]

Inflation Pressure

So... I started thinking about the inflation pressure and doing some research, and this is what I came up with.

Manufacturer Spec on a 1996 4Runner SR5 4x4 V6 requires 32PSI inflation on front and rear tires.
Stock size is P265/70r16
* P tires on a truck or SUV must have load rating divided by 1.1

I found the following general tables at:
http://toyotires-1524598101.netdna-...of_Load_Inflation_Tables_20150623_Final_0.pdf


P265/70R16 32psi 2115 LT lbs
LT235/85R16 50psi. 2205 LT lbs
LT285/75R16 35psi 2130 LT lbs


Comparison graph

[/URL]
The vertical line is the load rating of the OEM tire ant OEM pressure. Where this line meets the line for your tire tells you what the PSI should be.

Stock P265/70r16 tires at 32PSI have a load rating of 2326LBS. If the LT correction factor of 1.1 is applied, the rated load for our stock tires is 2115LBS. In order to obtain this load capacity with LT235/85r16s, the table shows inflation must be between 45PSI and 50PSI.If you do a linear curve fit to the LT235/85R16 tire, you get the equation:

PSI = 0.0338(LT Load) - 23.378
Insert 2115lbs for LT load and solve to get 48.1 PSI
I believe that the BF Goodrich employee I spoke to assumed that the stock tires are LT, not P. This is why he recommended 55psi.

Using the same method: a Load of 2115lbs on the following sizes
LT285/75R16 = 33.4 PSI
31X10.50R15LT = 45.3 PSI

Seems to be pretty logical, but use your best judgement! You would think the tire installer would know this stuff so they would inflate the tires correctly. According to this, my tires were 23% below the correct pressure when I left the shop!

 

[JayRolla]

Most tire installers just air to what is recommended on the door.

I have found that on high load tires that are aggressive like mud tires that I get a better ride and better tire wear at lower psi, I run 28psi on the street.

 

[CDNsldr]

Jcush87, Id love to see more pictures from the front and rear 3/4 views at normal standing height.

Ive got a rather large internal struggle going on between 235's and 265's lol. Not a lot of photos of 235's on 4runners kicking around

 

[tx_shooter]

I tried to put 235s on my 4Runner but the Lexus rims that were on it were too wide. Now that I am on TRD rims I am looking forward to getting on some 235s this winter. I am leaning towards some MT/Rs.

 

[Collkid]

Jcush87, Id love to see more pictures from the front and rear 3/4 views at normal standing height.

Ive got a rather large internal struggle going on between 235's and 265's lol. Not a lot of photos of 235's on 4runners kicking around

Bringing back a year old post......:fishing:

 

[Supermoney]

Jeez. Those must be rock hard. I use 32 psi in 285/75/16s