Outer Limits 4x4 Board

I have 33's on my GQ TD42, but lately I've been thinking about putting it back on 31's. It's basically a tourer and I don't need 33's most of the time, so I was thinking I could be better off with 31's as it would give me better acceleration and pull up highway hills better.

I've never driven my truck on 31's though, so maybe I'm kidding myself and the difference wouldn't be that great. It is a TD42 afterall, pretty slow.

What do you guys think?

well its about a 6% reduction and from my experience with trying different sized tyres...yes you will notice the difference but it won't be overly great.

I have a GQ LWB TD42 as well. When I had 4.1:1 diff ratios, I compared 31s vs 31s on one weekend. I did it to determine if I should upgrade to a 4.3:1 diff ratio. In town, the difference was close to none, but there were a couple of situations, where I thought it made a difference like long inclines where I could not shift into 3rd (Mt Victoria) or 4th gear (Putty Road) were not a problem any more.

I personally think, it takes the edge off the pain driving a 2.3ton gutless diesel truck.

Cheers
Joachim

If you don't need to run 33's then I'd go back to 31's.

Not only a situation of "less go" but also fuel economy will suffer, braking will suffer, and so will handling.


I would expect it to be more than 6% worse though, due to rotational inertia and other such issues. The weight difference in tyres is waaaaay more than 6%...



Having said that, I'm running 33"s and it depends on your diff ratios. There's a hill I drive regularly which is better with the 33's on because I can hold 4th rather than shift to 5th and then bog down...

Arnt 32's std? or the splitties that i think measure around this size?

Nic

Have done this exact same experiment. Lost a little bit when you put your foot down in 5th gear. I didn't do it long enough to get a good indication of fuel economy but i would think it is much of a muchness considering that it would take a little more to to get it up and moving but once up at cruizing speed should rev lower with the bigger rolling diametre of the tyres and therefore us less fuel.

The Conductor wrote:Have done this exact same experiment. Lost a little bit when you put your foot down in 5th gear. I didn't do it long enough to get a good indication of fuel economy but i would think it is much of a muchness considering that it would take a little more to to get it up and moving but once up at cruizing speed should rev lower with the bigger rolling diametre of the tyres and therefore us less fuel.

The extra height effectively increases your frontal area, and extra width of the tyres can add to aerodynamic drag too.

When I went from 31s to 33s my economy suffered - except one cool day cruising on flat ground with a tail wind.

If you don't need the extra clearance for offroad work, run the 31s.

Scott

mabsydney wrote:I have 33's on my GQ TD42, but lately I've been thinking about putting it back on 31's. It's basically a tourer and I don't need 33's most of the time, so I was thinking I could be better off with 31's as it would give me better acceleration and pull up highway hills better.

I've never driven my truck on 31's though, so maybe I'm kidding myself and the difference wouldn't be that great. It is a TD42 afterall, pretty slow.

What do you guys think?

When I went from 31's to 33's I noticed a noticeable diffrence in Brakes, power, and fuel.

See if ya can borrow a set of 31's for a week see what you find for yourself, everyone will have different results depending how they drive

cool so if take off my 36'' and replace them with the stocks,
i might be able to get it on its side....

Thanks for the replies if I can sell the 33's I'm thinking of fitting a set of 265/75 MTZs soon. Otherwise I'll have to wait til the STTs wear out and the rate they are wearing that will be a while!

nicbeer wrote:Arnt 32's std? or the splitties that i think measure around this size?

Nic

Yeah you are right actually and 265/75R16 is close to 32" give or take. So I guess I mean 32's really.