Yes, another tire size thread (285's at high altitude) (1 Viewer)

Joined
Aug 5, 2010
Messages
4,900
Location
Colorado
I know there are a bazillion tire size threads, and I have spent quite a bit of time digging through old threads and searching. I know general consensus is that 285/75r16 are fine with stock gearing, but on this forum and others, the majority of the "you'll be fine" responses in gearing threads come from people who live at low altitude or in a flat area. What I'm looking for specifically is personal experience from people who live in Colorado or other high-altitude areas.

When I bought the LX, the very first thing I did was drive it up I70 to make sure it could keep up with traffic. On 265's I can hold 70mph coming out of Denver up through Evergreen with no extra weight. I can even accelerate a couple mph. I am really hesitant to compromise the gearing at all. I don't want the truck to fall flat when carrying a load. I don't have the budget to regear at this time (and my inner cheap-ass says I might not ever). If the 265's weren't bald and didn't look so puny with this lift, I would probably just leave it stock.

So for those of you who actually drive regularly at high altitude (6,000+) at highway speeds, can you please chime in? What do you think of 33's?

I apologize in advance for :deadhorse:
 
Joined
Aug 14, 2014
Messages
210
Location
Buena Vista, CO
I live at 8000 here in CO, just bought an 80 with 285's on it currently. It is a little weak on the hills and definitely feels under powered at the moment. I plan on going to 35's sometime next year and will be going to 4.88's. Then I might still run the 33's in the winter because they are a good winter tire that are currently on the LC (cooper maxx ST).
 

SmokingRocks

I bought a Cruiser to keep miles off my Cruiser
Joined
Oct 6, 2014
Messages
3,362
Location
Colorado
I live in Alamosa CO (7500') my FZJ is a 93 with 156k well Maintained with BFG AT 33's no regearing. Last weekend I trailered it to Pueblo then drove it to FT collins then the top of Berthoud Pass.

From FT Collins to the top of US40 I had three adults, two dogs and about 200lbs+ extra in gear and coolers maybe 750lbs extra total. I was able to keep up with traffic on I-70 for the most part. I don't like to floor my 80 on the passes for extended periods of time, I feel it is too hard on my old girl, if she was new I would do it all day but shes 21 years old. So I opt to throttle to about 75% and stop there (I will go 100% at times but not for extended climbs). At the top of Floyd Hill I think I was at 55 (started at 75) but the top of floyd hill the speed limit drops to 55 there anyway.

I had no problem on I70 with this load going up to Eisenhower Tunnel I would think that I could average 55-65 mph depending on section without pinning the throttle.

Now US-40 is a different story, its a true pass with extreme switch backs opening up to solid gradients. Much slower here and had to drop down to 1st gear once (but you only go around the switchbacks at about 15-20mph anyway so its not that crazy). Just enjoy the drive and don't let people passing you get on your nerves. Even stock the FZJ is not going to rocket up the I-70 corridor.

Also click the ECT button when you are climbing into the hills and leave it on. It keeps you in the power band better than not having it on. Just get in the right lane and enjoy the drive.
 
Last edited:
Joined
Mar 30, 2014
Messages
200
Location
Cody, WY
I'm at 5,000+ for my daily commute, and day trips can easily bring me to 7,000+. I'm on 285s stock gears and don't have any problems. Sometimes on hills(especially with these nice Wyoming winds we have blowing head on) I feel a little sluggish heading uphill when I don't want to downshift and put the skinny pedal down because I know the hill is short and I can just regain speed at the top. I haven't had any problems otherwise.

Going through the chief joseph highway here on some of the steep inclines the 80 has no problem climbing them with the technique(posted by Landcruiserphil I believe? I'm unsure) of just downshifting to 2nd and holding the RPMs steady. The 80 has no problem pulling some STEEP hills this way and it ends up running cooler than just lugging it up in low RPM as well(according to my Digital Koso Gauge). I'm so fine with my gearing right now I actually just ordered 35s and should have them this week.

If I regear it will be to 5.29s simply due to the fact they offer more reduction and a slower crawl speed than the transfer case reduction gears on 4.11s.
 
Joined
Oct 22, 2002
Messages
4,482
Location
Durango, Colorado
I ran 295's for a couple of years. Drove all over the state with them. It's pretty much everything the 80 can do to almost keep up with traffic on 33's over 8000'

IMO the overall weight of your truck will have as much or more to do with climbing the passes at HWY speeds.

I'd expect to run 5-10% slower uphill on 285's pending grade and altitude.
 
Joined
Aug 26, 2009
Messages
5,791
Location
flat earth Midwest
BTDT with an FJ55. I haven't gotten the 80 to the real mountains yet, but know about what to expect. I worry less about road performance than about how things go in low range. I'm not too worried in that regard. On the other hand, I'be be dragging a trailer along, so it should be interesting.
 

fj80pb

SILVER Star
Joined
Jul 10, 2012
Messages
154
Location
WNC
You're right mate, there are zillions of threads on this (I'm even feeding the beast here) . But the number of posts won't change the math.

If one want to keep OEM specs: bigger tires=re-gearing. And there's no scape from this equation. Otherwise, there's a net loss in performance-only aggravated at high altitude...and the 80 ain't a fast rig to begin with...

Granted, many folks are happily living with 33', 35' even 37' shoes, w/o re-gearing, and a rather tranquil, unhurried-moving rig. And that's perfectly fine, it even “feels” right...for as long one is aware of what to expect.

If you drive most of the time at high altitude pavement/highway, expect to keep current performance, the stock size is the only rational option (w/o re-gearing). If, on the other hand, looks is an important consideration...well...your call.

Cheers
 

hamishpotter

SILVER Star
Joined
Dec 27, 2013
Messages
1,691
Location
NYC / CT
I see zillions of threads on loss of power due to +tire size. Does it have the same effect on braking? I don't mind chugging along down the road but I do occasionally worry about braking distances driving in urban areas. I'm assuming bigger tires should have bigger brakes, since the road side of the equation has a bigger lever with bigger tires. Is that true, and sorry for hijack
 

SmokingRocks

I bought a Cruiser to keep miles off my Cruiser
Joined
Oct 6, 2014
Messages
3,362
Location
Colorado
yes and no. The brakes will be adequate up to a certain degree. Idk what that is but I would bet the stock brakes can handle 37's and under just fine.

Obviously a truck wont handle, stop or go like stock. You can't expect it to, you are altering a intricately engineered product.
 
Last edited:
Joined
Aug 5, 2010
Messages
4,900
Location
Colorado
Well based on the responses in this thread so far, I may go ahead and stick with 265's or hope I have a couple extra grand sitting around by spring time.

I know it's not a rocket, but compared to a my 4banger mini truck, my FJ60 (or even my V8 swapped 62), it really does seem to have adequate power for driving up the hill. Not quite as good as my 5vz 4runners, but I think it would be on par if it had a manual transmission. I think I will kick myself if I end up dropping much speed on the way to the mountains or over the hill to Utah. I am not known to be a patient person, and neither is the :princess:
 
Joined
Aug 5, 2010
Messages
4,900
Location
Colorado
I see zillions of threads on loss of power due to +tire size. Does it have the same effect on braking? I don't mind chugging along down the road but I do occasionally worry about braking distances driving in urban areas. I'm assuming bigger tires should have bigger brakes, since the road side of the equation has a bigger lever with bigger tires. Is that true, and sorry for hijack

Yes, brakes are affected by tire size, but more for weight reasons than the actual tire diameter. The effect is less pronounced than power loss due to tire size.
 

Users who are viewing this thread

Top Bottom