Differences on gearing between 235/85 and 255/85

[Aaron]

G`day guys.

What differences could one expect between 235/85’s and 255/85’

Also, how much of a difference would the turning circle be. E.g – would a 3 point turn become a 15 point or just say a 5point.

Cheers
Aaron

[roverrescue]

Pilfered from BFG MT KM2 website...

LT235/85R16 120/116Q diam 32" 650 revolutions @ 70km/h

LT255/85R16 123/120Q diam 33.3" 625 revolutions @ 70km/h


So in that particular tyre there will be a 4% variation in gearing between 235 and 255.


Steve

[Aaron]

Thanks for that.

So low range decents will become even slower, and highway driving will require higher engine rpm?

[roverrescue]

depends which way you are going.
235s will require more revs for a given speed over ground (not what the speedo says it will change) than the 255s and similarly, in low range 235s will give you 4% deeper gearing. 4% aint much though.

255s are a great tyre size, good height for clearing a sals rear diff, not too wide.
Only problem is the limited number of tyres made in 255/85R16.

Steve

[Aaron]

excelent, thanks for your help!

[rick130]

The difference between worn out 235's and new 255's is closer to 7% just going off my speedo readings.

Yes, the bigger tyres bugger up the turning circle, particularly on a 130 but you get used to it quickly. It's only when you jump into a GU Patrol and you do a U turn easily in the space a 5 point turn needs to be made with the 130 that you curse :D

AFAIK, only BFG MT's, Maxxis Big Horn 762's and Cooper ST's are available in 255/85/16 in Australia.

[long stroke]

We have just put 33/10.5/15" bfg mt's and to be honest the only thing we have niticed is the speedo being a tiny bit out;)
Gearing is still fine:)
We are running slightly wider off-set rims so don't lose any turning cicle:cool:

TIM.

[Aaron]

Im try to find out if Toyo do a 255/85. The Au site doesn't list one, but they're talked about on US sites. They look pretty good, a bit more open than a Bighorn.

[rick130]

Im try to find out if Toyo do a 255/85. The Au site doesn't list one, but they're talked about on US sites. They look pretty good, a bit more open than a Bighorn.

Dunlop do their aggressive MT in 255/85 for Europe, but not here, but the more people buy this size, the more likely it is that importers will bring them in.
IMO it's a great compromise.
oh, and the Maxxis is a bit bigger in the bag/wider than the BFG too, you can notice it when they are fitted, possibly 8mm or so.

[rick130]

We have just put 33/10.5/15" bfg mt's and to be honest the only thing we have niticed is the speedo being a tiny bit out;)
Gearing is still fine:)
We are running slightly wider off-set rims so don't lose any tyrning cicle:cool:

TIM.


They are slightly smaller than a 255/85.

Static loaded radius of 378mm vs 389mm for the 255/85. 394revs/km vs 388.

[omy130]

When I 1st swapped to 255/85/16, the standard 300Tdi really ran out of puff. Since tweaking a few things, it travels great. As for turning circle, my 130 rubbed previous tyres. The 255's roll better over bumps. I don't think I'll change to another size for a while.
Geoff

[OZ Landy]

What few things did you need to tweak?
What rims size do you need to run the 255s?

Cheers guys

[Aaron]

I got the 235's fitted. they suited my needs a bit better.

[rick130]

What few things did you need to tweak?
What rims size do you need to run the 255s?

Cheers guys

255/85's are legal on 6.5" rims, so 130 rims are good to go.

Tweaking generally refers to adjusting the pump fuel settings, generally in the aneroid/boost compensator, but can include an uprated intercooler, bigger exhaust, etc too.

Pump adjustment tutorial for the 300Tdi is here http://www.aulro.com/afvb/attachments/technical-chatter/326d1152411367-how-get-more-hp-out-tdi-300-thermoguard-20tdi-20tuning-20rev.2.pdf

[1103.9TDI]

How do the 255/85's compare to the 265/75's in terms of diameter?. The 265/75 seems to be a very common size with heaps of choice/competition. They also fit on a Disco/130 rim.

[rick130]

How do the 255/85's compare to the 265/75's in terms of diameter?. The 265/75 seems to be a very common size with heaps of choice/competition. They also fit on a Disco/130 rim.

265/75's aren't legal AFAIK on a 130 rim, (7" and up only) and they are roughly the same diameter as a 235/85, at least within a couple of mm when new looking at most manufacturers charts.

eg. BFG list the 265/75 MT at a static loaded radius of 371mm, 235/85= 378mm and 255/85= 389mm

Maxxis list the 265/75 Big Horn at 31.8" vs 33.3" for the 255/85 and I've verified the 255/85 size when I bought mine.

[Aaron]

For those interested in how the tyres are.. I love them. These are my first mud tyre, so cant compare to others

Hit the mud yesturday, did a pretty easy red clay accent. Half way up, 2nd low im starting to slip back down. Then I remembered the idea with Mt's was to spin the mud out of them to keep the tread clean. So i gave it a squirt and hit boost, and they bite hard :P

On road they're nice. On smooth road at around 80 you get a mild hum, but who cares.

For the record, I got 110k out of my General Grabbers

[MacFamily]

What size and Brand did you get Aaron? pics pics :D

[Aaron]

235/85 R16's Bighorns.

Pics ill upload soon. Shoot us a pm if your about to buy some, Ill tell you where I got the best service/price.

[MacFamily]

235/85 R16's Bighorns.

Pics ill upload soon. Shoot us a pm if your about to buy some, Ill tell you where I got the best service/price.


Pm sent

[Aaron]

https://www.aulro.com/afvb/images/imported/2013/10/1050.jpg
https://www.aulro.com/afvb/images/imported/2009/03/868.jpg
https://www.aulro.com/afvb/images/imported/2009/03/869.jpg