WG tire diameter & gearing affect?

[Forest]

Hi, I will soon need to buy tires for my WG 4.7. I would like bigger tires but I am wondering how much bigger I can go before I notice an increase in gearing? I am only thinking a 265 65R17 AT but I tow a Jayco camper and fuel consumption is a consideration. Does anyone out there have any first hand experience in this area and could offer some advice?

[drover]

Just to clarify has your WJ got 16's or 17's on it ??? If you do a search there is a thread on tyre/rim sizes and all the info you need. Pretty sure a 265 will scrub, it will on a 16.

[fester]

Mine had 265/65x17 with a 2" lift when I got it and they rubbed on the inner wheel arch and the lower control arms. Didn't really cause any issues but without a lift I expect it would be much worse.

Can't help you on the gearing etc as they were there when I got it so nothing to compare to and I also have the diesel. Can't say the diesel feels any worse for it and fuel consumption doesn't appear much worse than others are getting but that is hard to compare too as I'm now running 265/70 M/T's which don't do any favours for fuel.

[drover]

this might assist with sizing http://www.carbibles.com/tyre_bible_pg4.html

[Forest]

Thanks for the replies.
and thanks for the carbible link that pretty much puts all wheel tire info in one place.

My wheels are 17" and I realise a lift &/or spacers will be required. I have my eye on some 17" JK Moab wheels that have a 44 mm offset compared to my 51 mm overland wheels.
The thing that is unknown to me is how much a ~ 5% increase in tire diameter will affect the gearing in on my V8, will my seat of the pants dyno notice it?

Cheers.

[drover]

I think if you dig into that carbible site it covers that, need a calculator though. It will depend on the circumference, tyre/rim size means nothing, the difference in circumference will determine it but then if the vehicle originally came with 16" you will have to really do the math.

[mikehzz]

I've got 245/70/17 General Grabber AT2's and they are only 1mm smaller than 265/65/17 according to the tyre size calculator. I don't have a lift and they brush the wheel arch if the wheel gets pushed fully up. It hasn't worried me and they are way better off road. The speedo now reads 7% slower as does the odometer. This throws the trip computer out by that much too so you think your fuel consumption has increased but it's mostly because of the tyre diameter change fooling the computer. There will be a slight increase because the wheel mass is bigger. Haven't really noticed much change power wise in the gearing. Mine's a crd 2.7.