Wheels & Tyres

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From Brian Westley:

I'm new to the OKAs and this site so HI to all. My query is regarding 16" versus 19.5" wheels. Looking at the OKA from the rear it seams that the wheel base is narrow compared to the body and that by fitting either wider wheels and or tyres then the stability of the body would be increased. I use my OKA mainly off road or on winding roads for High Country 4WD tours and am wondering if anyone has any comments / suggestions on this subject.
Thanks
Wessa
May 31, 2010 at 8:27 PM Flag Quote & Reply

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From David Hallandal:

What tyres/rims do you have now?
I have 19.5" rims and would not go back to the 16" rims.
if you have standard 16" split rims the biggest you're going to get on is the 900/16 or believe they are now 255/16 (I think).
For 19.5" rims then on a standard OKA 19.5 x 7.5" wide rim you can go to a 285/70R19.5 tyre. If you get rims made then get 19.5 x 8.25" which allows you to run the 305/70R19.5 which is what the current NT now has as standard and is what is on my OKA. I love them they have been through the High Country, Flinders Ranges, sand driving at Robe and across the Anne Beadell Hwy all the time performing very well in all situations I have put them in.
David Hallandal
May 31, 2010 at 8:31 PM Flag Quote & Reply

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From David Ribbans:

Wessa,
Okas are quite high vehicles, which is great for ground clearance but it raises the centre of gravity, which is the main cause of body roll and stability concerns.
My suggestions are to ensure you have good strong shock absorbers to control body roll (or to fit airbag suspension, like David H and others have) but most importantly, keep the weight as low down as possible (eg. no roof racks carrying heavy weights like spare wheels and jerry cans).
You can't do much about the track width and I doubt that wider wheels and tyres would help stability very much. They might help with traction but are also more expensive. Lowering the tyre pressures is the best way to improve traction.
I have 285 width 19.5 inch tyres and find them fine but I'm told 16 inch wheels can improve the ride and traction although split rims have other disadvantages.
David
May 31, 2010 at 8:33 PM Flag Quote & Reply

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From Peter_n_Margaret:

Wessa, our OKA196 had 265/70R19.5s fitted when we bought it (it was an ex tour bus).
They were B-awful! Very hard ride, bogged if it saw sand 100m away.
It also came with a set of 16" and I tried them too. It was a different vehicle. Softer ride and better traction.
Because of our weight, I eventually fitted 305/70R19.5 Michelin XDE2 tyres.
They are not quite as soft as the 16s, but a world away from the 265s.
We are getting 65,000km plus out of them (they chip quite a bit). I have heard of tour operators claiming 100,000km.
We manage all sorts of terrain on them and have never scrapped a tyre that is not 90% worn out.
Cheers,
Peter
May 31, 2010 at 8:35 PM