Inevitably, someone always asks how big of a tire you can put on a Gen1 Monty or Raider and we always point people at the tire fitment chart, and rxinhed shows all his different configurations and says how great they all are. Then, someone almost always chimes in and says "If you go with 31's you'll lose tons of power, 33's will be a LOT worse" or something similar.

My experiences:

The truck: 341k miles, 2.6L 5 speed Raider. Stock, no mods.
The tires: 31x10.50x15's on 15x8 steelies with unknown, but wide offset.

I started off with the stock 28-ish tires, then went to 30's. The first thing I noticed was the that the truck sat just a smidgen higher. Cool. I didn't notice much difference except that it betrayed a worn idler arm with a slight wobble.

Then I went, a year later, to 31" tires. Again, it sat a little higher. Cool. I notice a bit of a difference between 30's and 31's.

The positives:
The 31" tires seems to compensate for what I consider to be too-low of gearing in these trucks. Stock is 4.62 gears! With 31's, over the original 28's, its the equivalent of swapping in 4.17's, which is much closer to the 4.10's that many trucks come with, and I find that the truck is quite a bit peppier when I'm up to speed. From a dead stop, the difference is minimal and if the truck is on level ground or even the slightest downhill, I can start in second if I want to. The truck is in its power band at more common speeds, and I can now zoom up steeper hills doing 55mph (indicated on speedo, not corrected) in 4th gear whereas I before did 45mph in 3rd. I personally think this has to do with matching the power band of the motor to where its needed, a lower down in the RPM range for the same actual MPH.

The negatives:
As mentioned my truck is very high mileage. I know it needs a ball joint and a TRE to be perfect. With the 30's I hardly noticed, but with the added weight and width of the 31's, I notice. The truck pulls a little now. But thats not the tires fault.

I'm at 4500' in the Reno NV area. Next week I'm moving very close to sea level in Washington state, and will report any changes that I notice over time with the higher air density there.

Overall, I am VERY glad I put 31's on my Raider and I'll do it again in a heart beat. In fact the next tire will likely be 33x10.50's if I can afford them.

To be clear, I did not like the 32x11.5 all terrains on stock 6-inch wheels. The truck was squirmy when taking downhill corners at speed, I think due to sidewall flex. Looked good, drove poorly.


<img src="/forums/images/graemlins/sleeping.gif" alt="" />

Must be me... But on the 10 plus years of being on this forum I cant seeing that as the general consensus on going to 31's, or that as being the canned response.

Its interesting how people can have such a different experiance doing the same thing.

One thing I noticed is the if you have an auto the larger tires seem to have more of an effect. I have done tire upgrades on both the stick and the auto 2.6 Raiders. My experiance was with each tire size increase the vehicle got a little slower (28" 30's and 31's).

I never noticed more pep from spinning the engine slower. That assumes I'm shifting at speeds under 5400 RPM. PAst 6000 RPM I noticed the power drops off pretty quickly. If my 2.6 had more pep turning slower I would have the hood open trying to figure out what was wrong. <img src="/forums/images/graemlins/oink.gif" alt="" />

I'm curious about your your take on stopping on the highway with the taller tires and the stock brakes on an 87.

Kevin

I'm not saying its the general consensus, OR the canned response- just that there's always somebody saying it.



I've never revved my engine past 5000rpm, and I didn't like spinning it that high really. My engine seems to be happiest between 3000 and 3300 rpm, but maybe its me thats happier at those speeds. Which brings up another question: how high can you rev a high mileage 2.6L and for how long? But thats another discussion.


Completely satisfied with it, but I don't do a lot of freeway driving.

Just took a quick look, and the 2.6L puts out the most torque at 3000rpm, and that is now accessible at freeway speeds in 4th and 5th gear due to the slightly larger tires. I think that's why I'm seeing what I perceive as better performance with the 31's.

http://www.4x4wire.com/mitsubishi/tech/engine_specs/

That's my story and I'm stickin' to it ;-)

I've run 31's on my SWB 2.6L, but that was with 15x7 Toyota alloys and Gen II alloys. IMO, 6" isn't wide enough to safely run 31's, and it looks funny (i.e. those beads are pulled WAY in towards the rim). They look fine on 7" wide rims, but not 6". And to be honest, next go around on tires I'd get 30's, to give that 4-cyl a break on all that tire/wheel rotating mass.

And so does BFG. I would think that other makers also suggest a minimum 7" wide rim for a 10.5" wide tire. But then again, a lot of this comes down to driving style. If you're a take it easy kind of driver you'd probably never even notice a difference. <img src="/forums/images/graemlins/kewl.gif" alt="" />

This whole response covered my 88. I'm running the 32X11.50 BFG All Terrains, and they definitely are too wide for "sporty" driving. But they do real well off-road. But I'm a take it easy kind of driver and can work with it as it is. BTW, these Gen 11 alloys everyone speaks of, are they all supposed to be 7" wide. The alloys on my 94 SR rims are 15X6's. Did I get gipped?

35's on a 15x10 wheel is awesome, everybody should go that route <img src="/forums/images/graemlins/smile.gif" alt="" />

True. Truck went wherever it was pointed with them!