Harsh ride after tyres being fitted

[awbeattie381]

I have posted this on the Victorian pajero page so apologies to anyone reading this twice!


Ive recently replaced the standard size wheel and tyre combo on my 1989 NG to a 31/10.5 R15 Kumho Venture AT. They have given me an extra inch of clearance and are great off road.

I thought by going to a large tyre (in this case 2 inch difference in height side by side - new next to old) the bumps should be slightly less noticable. The car amost rattles to pieces the minute it drives over broken bitumen. Im running between 34-36 PSI and looking at the profile of the tyre seems underinflated.

Ive put it down to the make of the tyre (sharp shoulder and thick sidewalls). Im not too happy. im rather dissapointed as im wanting to go back to my old setup which lies under the house.

Would the tyre be the issue? Anyone running this tyre and what do they think if they have had experience with other tyres?

[RoldIT]

Tyre could be out of round.

Kumho aren't exactly KNOWN for their high quality ...

[-Scott-]

Hi Andrew

You haven't mentioned the pressure you ran in the old tyres - I presume it was comparable?

The only other thing I can offer is that almost every change I've made in an attempt to improve off-road ability has detracted from the "feel" of the vehicle on-road. You're not alone...

Scott

[J Top]

Take a picture of the tread contact patch by letting a wet piece of tyre down ,off a jack,onto a piece of paper or cardboard and get an accurate idea of correct pressure.
I used to sell Kumho's and got good feedback from customers.
I always ran them at 35psi.
J Top

[awbeattie381]

I think I ran the old tyres at about 34 (front) and 32 (back)

I might fiddle around with pressures....just by looking at the top of the tread it seems to dip a little in the middle indidcating that the pressure is too low. I might try the wet tyre on a piece of cardboard trick this weekend. Maybe it is the pressures. thanks for the replies.

[dinos4x4]

Its does not matter what brand or style the tyre is , at road pressure you will feel every little bump

when i am off road and dont need to do any high speeds i run my tyres at about 25psi makes a big differance

[Alex Kogan]

My Gen II came stock with 31" label calls for 31 upfront and 40 fully ladden rear. So for regulare rides to work/store you could keep rear at lower 30 as well.

[ianmc]

A baggy 31x10.5 should be able to support the Paj unladen at a lower pressure than the original smaller tyres. If you run at 34-36 unladen you will surely wear out the centres & be up for early replacement.
Have had some funny figures given by tyre "Professionals" for correct
pressures eg 35psi for light Triton ute when on 30x9.5;s.
I ran them at 28psi & they wore very evenly & well & gave a good ride.
I;d say try 28psi for the 31's & see if the look right, handle OK & ride well!
Then bump up the rears in particular when loaded.

[awbeattie381]

sounds like a plan. I double checked the pressures on the weekend and they are 34 all round.

Will drop the front to 30 and rear to 28. will see how that goes. thanks for the replies.

Andrew

[awbeattie381]

just an update - had a day trip in the bush 2 weekends ago and confirmed my hate for these tyres. They are great offroad by suck on road. I struggle to corner comfortably on open roads at 90-100km/h. It sways and seems inconsistent with sterring and its ride. Ive let the pressures down to 30 and 32.

Prior to trading in my current 15x7 chromies i had 15x7 sunraysias with the old 31s kumho AT tyres fitted. they were almost bald but were the older tread design with a more blunt shoulder. The car handled unreal on the open road - confindent, consistent and was a general pleasure to drive.

Im now wondering if its the rim itself. Can any tyre be this crap on road if its only an AT? Should i be blaming the rim or the tyre?

[-Scott-]

Andrew

"Sway" like you describe can be caused by sidewall flex, generally produced by pressures too low. I was running my 31s at 38psi on road.

Handling and ride comfort are always compromised when it comes to tyre pressures. Are you sure you're not expecting too much?

Scott

[awbeattie381]

it may be the sidewalls flexing - ive never experienced this 'swaying' before. There is always a compromise with tyre pressures!!!

I thought i was expecting too much but thinking back about the sunraysias running 31s and the older style tyre, the handling was awesome and the ride was not at all harsh!

Some of my steering components (bushes) also need replacing prior to my pink slip - there is a bit of slack in the steering wheel.