Strange noise and jeep behaving strange

1853 Views 13 Replies 6 Participants Last post by Jeep Trick, Jan 20, 2012

SRT8ScoTT

Discussion Starter · Jan 19, 2012

Right this is really hard to explain but ill do my best...before i had a problem with my TC when i got the wrong tires..i took out the TC motor and all was fine until new tires were finally delivered! my setup is now 255/45/20 - 275/40/20 ..re-attached my TC motor (service 4wd system went away) and that horrible noise was gone...HOO RAY i thought...but when i go around a roundabout kinda hard theres a very strange noise coming from the left front side and the brakes dont feel confident to brake..as i come off the roundabout i thought id give it a boot but was held back by the ESP for a good 3-4seconds! also when i accelerate at high speeds i can feel the front of the jeep lift and i find it very loose(as if torque steer) i get this when i launch aswel...thing is when i was running my standard 245/45/20 run flats all round accelerating at high speeds was a breeze and launching was perfect....it just feels very strange at the moment and i honestly dont have a clue whats going on?

Any help on this would be appreciating thanks!

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1 - 14 of 14 Posts

TheBRICK

· #2 · Jan 19, 2012

What kind of tires are they?

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SRT8ScoTT

Discussion Starter · #3 · Jan 19, 2012

[email protected] said:
What kind of tires are they?

ive kuhmos on the rear and bridgestone up front! i know i shouldnt mix tires but at least each axle has the same....i live in ireland and its near to impossible to find tires so getting tires is like winning the lotto for me!

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TheBRICK

· #4 · Jan 19, 2012

Does the rolling diameter match on these?

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SRT8ScoTT

Discussion Starter · #5 · Jan 19, 2012

[email protected] said:
Does the rolling diameter match on these?

Ha ye the do..i triple checked before buying on numerous sites! also i match them up when just before putting them on and also when i had the 245/45/20 - 255/45/20 the noise from the TC is now gone and it feels smooth changing through the gears! but its just this lil problem im having...just fretting about it because i know its not good

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TonySRT8

· #6 · Jan 19, 2012

shouldn't it be a 285 instead of 275 for the rear wheel.

Going by the specs you gave in post #1
255/45/20 gives a 91.218 inch wheel circumference and
275/40/20 gives a 90.042 inch wheel circumference

a 285/40/20 would give a 91.032 inch wheel circumference, which would be a closer match.

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StangSlayerMA

· #7 · Jan 19, 2012 (Edited)

SRT8ScoTT said:
ive kuhmos on the rear and bridgestone up front! i know i shouldnt mix tires but at least each axle has the same....i live in ireland and its near to impossible to find tires so getting tires is like winning the lotto for me!

What model tires?
I see a Kumho Ecsta STX in a 275/40/20: 28.7 overall diameter.
and a Bridgestone Dueler H/P Sport in a 255/45/20: 29.1 overall diameter.

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SRT8ScoTT

Discussion Starter · #8 · Jan 19, 2012

TonySRT8 said:
shouldn't it be a 285 instead of 275 for the rear wheel.

Going by the specs you gave in post #1
255/45/20 gives a 91.218 inch wheel circumference and
275/40/20 gives a 90.042 inch wheel circumference

a 285/40/20 would give a 91.032 inch wheel circumference, which would be a closer match.

well 2 problems with that...ive the export 8" rim so i doubt 285 would fit also when looking no one here does 285..they do a 315 (for the x5) but that comes with 275 for the front so they dont bother with 285....he does have another set of 275 maybe i should just buy them and run 275/40/20 all round ??

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SRT8ScoTT

Discussion Starter · #9 · Jan 19, 2012

StangSlayerMA said:
What model tires?
I see a Kumho Ecsta STX in a 275/40/20: 28.7 overall diameter.
and a Bridgestone Dualler H/P Sport in a 255/45/20: 29.1 overall diameter.

ye spot on those are the models....interesting there because i did fret about this to the tire dealer (who said "he knows his stuff") and said that that would be fine diameter wise....but if its off why is the noise from the TC gone?? ha seems to be a love hate relationship with owning a one of a kind jeep in ireland!

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StangSlayerMA

· #10 · Jan 19, 2012 (Edited)

SRT8ScoTT said:
ye spot on those are the models....interesting there because i did fret about this to the tire dealer (who said "he knows his stuff") and said that that would be fine diameter wise....but if its off why is the noise from the TC gone?? ha seems to be a love hate relationship with owning a one of a kind jeep in ireland!

The difference in diameter between the front and rear tires is .4, where .3 is the max allowable difference. Not sure why the noise went away....maybe it just isn't so drastic of a difference to cause a noise, but enough to cause a binding issue.

This is going by manufacturers specs....they are not always exact.....and one of your pairs of tires was already on the truck, so that measurment could be different as well.

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SRT8ScoTT

Discussion Starter · #11 · Jan 20, 2012

StangSlayerMA said:
but enough to cause a binding issue.

hmm binding issue?? take it this isnt a good thing?

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Rose City GC SRT8

· #12 · Jan 20, 2012

Your tire diameters differ by 1%. That is good. Max allowable difference is 3%. I think your TC may be having a problem. Check the fluid and change it if it is black. When was it last changed? It should be changed every 10k miles.

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StangSlayerMA

· #13 · Jan 20, 2012 (Edited)

SRT8ScoTT said:
hmm binding issue?? take it this isnt a good thing?

When you are just cruising the AWD is 90%/10%, with most power going to the rear. Every time the truck detects wheel spin, it tries to put more power to the front diff, up to 50%. If the rear drive shaft is spinning at one speed, and the front drive shaft is spinning at a slower speed....you will burn up the clutches in the transfer case.

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Jeep Trick

· #14 · Jan 20, 2012

You should have 9" wheels all around on the export model

I hear you on getting tires there but running different manufactures front and back is like wearing a size 10 Nike on one foot and a size 10 Adidas on the other(or how ever you do your shoe sizing there

). It is unlikely that they will fit the same as there always seems to be a slight difference in size for every shoe manufacture. Unless you had a tape measure (on of those flexible ones that tailors use) to put on the outside diameter of the tire I would wonder if they are sized accurately. Now if this was a two wheel drive vehicle it wouldn't matter but the jeep is kinda picky. JMO

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