Thread: 255/85 and puma highway revs

Originally Posted by Steve A

Can any body tell me what revs a puma defender runs at with 255/85 tires in 6th on the highway. I'm concerned no to over tire and drop revs/torque at 100 kliks

Can't recall off the top of my head, but it's a non-issue, actually corrects the speedo error!

My Puma carries a lot of weight and runs 255s, I've done a few performance upgrades which act to offset the gearing issues, but to be honest it's more about the weight I carry!

Thanks for the reply,

I plan to install a chip and some type of high flow muffler. Do you have any suggestions? Not sure if an add on chip or reflash ECU is best.

Tire choice I am looking at the Good Year Dura Track muddie, 255/85

Originally Posted by Steve A

Thanks for the reply,

I plan to install a chip and some type of high flow muffler. Do you have any suggestions? Not sure if an add on chip or reflash ECU is best.

Tire choice I am looking at the Good Year Dura Track muddie, 255/85

I'm running a Bell Auto remap, a modified standard exhaust and an Allisport intercooler. Davis Performance is a good local option.

A chip is a very low rent option compared to a remap.

Didn't think they brought the Duratrac into Oz in that size? I'm running BFG KM2s but I'm not today impressed to date - I've been having ongoing balancing issues (though all other performance aspects seem pretty good so far).

100km on 255/85 sits at 2000rpm.

Originally Posted by newhue

100km on 255/85 sits at 2000rpm.

Yep second that.. Had my 255's fitted a few days ago and sits on 2000rpm at 100. I would have to say a bit more power would be useful as you do notice the gears being a bit longer and feels a tad sluggish compared to the 235/85

Originally Posted by defrover

Yep second that.. Had my 255's fitted a few days ago and sits on 2000rpm at 100. I would have to say a bit more power would be useful as you do notice the gears being a bit longer and feels a tad sluggish compared to the 235/85

I eventually put a BAS tune in mine. Yes I found the step up from 235 to 255 though only 1", a noticeable performance change happened when it came to accelerating. Same with braking. The tune however removed that response lag, and I got accustomed to braking earlier.
The tune also works in reverse with the car going that bit better again when going back to 235's.
For me, the intercooler I added before the tune gave me and obvious performance difference of about 1/2 of what the tyre sizing does. So there's not much in it. Not sure if it was worth $800, but it's nice to think on those hot days the donk is getting the coolest air available. The tune is worth every cent of the cost.

Originally Posted by newhue

I eventually put a BAS tune in mine. Yes I found the step up from 235 to 255 though only 1", a noticeable performance change happened when it came to accelerating. Same with braking. The tune however removed that response lag, and I got accustomed to braking earlier.
The tune also works in reverse with the car going that bit better again when going back to 235's.
For me, the intercooler I added before the tune gave me and obvious performance difference of about 1/2 of what the tyre sizing does. So there's not much in it. Not sure if it was worth $800, but it's nice to think on those hot days the donk is getting the coolest air available. The tune is worth every cent of the cost.

The intercooler is worth it for the reduction in EGTs - particularly when you're towing on a stinking hot day!

Regardless of your tyre size the tacho will indicate the same revs at any indicted speed on the speedo.

It is only the actual speed that will change.

You will have to use your GPS to measure your actual speed, the tacho will be correct.