How big is too BIG(tyres)
Submitted: Saturday, May 27, 2006 at 21:48
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Member - Nick (Kununurra)
About to replace the tyres on our HZJ105 and dont know whether to get bigger tyres or std ones.Wouldnt mind to go to 285's for a bit of extra clearance but how much will I gain.Is it worth it as speedo will read out,reads perfect now(265),proberbly use a bit more fuel to turn them over to,how will it effect low range gearing.When we eventually go back to Tassie I will be fitting a turbo to it so that will help spin them over.
Any of you who have one,if you were replacing your tyres what size would you go for??
Thanks all Nick
Reply By: Willem - Saturday, May 27, 2006 at 22:04
Saturday, May 27, 2006 at 22:04
Nick
My thoughts are that the advantages would be negligible and the negatives...
well maybe a disadvantage...lol
I am happy with 265's and a 50mm OME lift
On my last trip one of the participants was running 315's on an 80 series. It was jacked up so high that riding in it was pure hell for the passenger and the driver felt it too. Admittedly this was in rough country, but still. The vehicle bounced and swayed like a palm tree in a stiff breeze.
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Follow Up By: Member - Roachie (SA) - Saturday, May 27, 2006 at 22:26
Saturday, May 27, 2006 at 22:26
G'day Willie,
I agree with you to a certain extent, but have recently discussed this with
John and it turns out his shockers are stuffed......his 80 series (as much as it gawls me to admit it...hahaha) is a very capable and stable vehicle normally, but with buggared shockers it would be as much of a handful as anybody could imagine.
Cheers blokes
Roachie
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Follow Up By: Willem - Sunday, May 28, 2006 at 09:36
Sunday, May 28, 2006 at 09:36
G'day Bill
Hmmmm yes But the higher the centre of gravity the more
Rock'nRoll go are going to get.....unless ofcourse you fit dual shocks and then you start getting to the overkill stage. You know all about overkill, eh????....LOL
In the country we drove across anything, but a truck with flat leaf springs, would have bounced and swayed quite a bit. I believe there is some good video footage of my rig and trailer contorting at all angles.
Cheers
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Follow Up By: Rock Crawler - Sunday, May 28, 2006 at 12:47
Sunday, May 28, 2006 at 12:47
I recall a trip last year that some on here who loved following a certain 80 series with 315's .
If I remember correctly , was stated that it was like driving behind a gratter
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Reply By: Member - Captain (WA) - Sunday, May 28, 2006 at 06:46
Sunday, May 28, 2006 at 06:46
Hi Nick,
On my old 1HZ 80 series I originally had 31x10.5R15 BFG TA's (equivalent to 265/70R16 dia) and changed to 33x10.5R15 (equivalent to 285/75R16 dia). Apart from the obvious differences like ground clearance, the thing I really noticed was just how much better it performed in sand.
In
places I had to let the 31's down to 20 psi to get thru I could get thru on road pressures. And once down to 15psi on the 33's the vehicle was virtually unstoppable, whereas before I would really struggle to get thru. Overall, it was a significant improvement offroad that I was not expecting to be so noticeable.
As for gearing, I did not notice any real difference on or off road. The 80 was already pretty low geared so on road it was if anything an improvement. Offroad the extra performance more than made uo for any change in gearing. The speedo was out by 6%, but I used the GPS anyway.
The improvement was significant enough that when I got my brand new GU, I went straight from the dealer to the tyre
shop and had the original 265/70R16's changed to 285/75R16 Cooper ST's before the vehicle even got
home.
Cheers
Captain
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Reply By: Member - John L G - Sunday, May 28, 2006 at 12:43
Sunday, May 28, 2006 at 12:43
Nick,
My son has these, 285/75/16 on his 100series 1HZ turbo and intercooled.
There is heaps of room under the gaurds and the thing is fantastic in the soft stuff compared to the 265's or smaller diameter jobs.
Vehicle still handles
well and no undue body roll. Does dont affect power in real terms as the vehicle doesn't seem to settle in the dirt as the other truck so methinks it is always climbing that smaller
hill just in front of the tyre we all talk about.
YES. The speed is out about 6km per hundred but I understand that can be fixed. We just factor that in when we drive.
Have fun. My advice would be to go for it.
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Reply By: Crackles - Sunday, May 28, 2006 at 21:19
Sunday, May 28, 2006 at 21:19
Nick......Had a set of 255/85/16 BFGs & now running the 285/75/16 MTRs on my HZJ105.
Both tyres have a similar diameter & both fit comfortably under the wheel arches without touching, in fact I've occationally run snow chains on them both without any issue. On the road the bigger tyres are harder to push & the standard diesel engine does struggle a little on the hills reducing the fuel economy slightly. With a turbo you will barely notice any problems. The difference offroad is noticeable, particually in deep mud where the extra ground clearance helps you reach the bottom of ruts & clear the diffs over rocks & ledges. Forget the speedo being out as after a while you'll automatically compensate by slowing a touch anyway.
In low range it's almost impossible to notice the slight ratio change & certainly doesn't effect climbing ability or engine braking.
One possible problem is that the bigger tyres MAY contribute to additional strain on the front diff which as we know can be a problem on the 100 series.
Any larger tyres than the 285s particually on the standard diesel do better with new diff ratios to compensate.
If you do a fair proportion of challenging 4x4 driving then the 285s are definately the go. If you spend alot of time getting there or tow frequently the 265s may be more suitable.
Cheers Craig.....................
HZJ105 Vic
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