98 2.5 barely makes it to 65 MPH

J

Jainee

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Oct 19, 2019
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Texas
I have 98 TJ with Rough Country 3 and 1/4 suspension lift and no body lift. The gear ratio is 5.13.

currently I have 15” dick cepek rims and 33 12.5 15 Mickey Thompson M/T tires.

it runs good at 45, and starts showing sluggish and struggle at 55. I could barely make it to 65 and it’s becomes scary ride.

I also have 2020 JL 17” rims.
I’m looking for recommendations if there are any better tires which could reduce weight and give better ride?
I did read a lot and 35” isn’t recommended. Will it change the behavior with 17” wheel?
Or if I get 33” (or say 34”) different tires on 17” - will it change ride?

I also know there are multiple threads around it. I’m checking if 15 vs 17 rims and tire size combo makes a difference?

3BD8C63C-F02C-40C6-A19B-B483140F5D89.jpeg
 
You have some high rolling resistance there with those tires.
That said....your ride. If your ride sucks I'm betting 1 of 2 things. Maybe both.
I bet your shocks are rough country. They blow dog. Bad.
Second...I bet you're running too much air pressure. With that tire you only need 20-22 lbs.
Yes I'm serious.


Why do you have sport stickers when it's an SE Jeep?
Get them off there. People have more respect when you're proud of your 4 banger instead of false packages.

You're up against the gear wall with 5.13's.

Your speedo will be off about 12-15 percent.
So 50 mph is actually 56-58 mph.

65 mph on the speedo will be about 73-75 mph

Unless you changed your speedo gear?????

17's will ride worse. Get better shocks and lower the air pressure. It will feel like a new machine.


Good luck.

P.s.

If you're really having a hard time hitting 65 mph...legit 65mph...

Realize the 2.5 isn't a power house. Not in the slightest. You've got about as much gear help as you can get.

Being a 98 perhaps you're in need of a tune up? The cat condition is? If it's starting to plug up that will hurt power.
 
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Thank you!

I didn’t know and I will take off the sticker. :)

you are right, rough country lift kit shocks. Currently it’s in shop and I’m looking for changing shocks to Rancho or Bilstein or fox shocks.

I have 26 psi and the tooth speedo gear was changed.

I agree and I don’t expect it to run at 70 mph on freeway and I was checking if in case changing tire and rim combo could help.

thank you again! This is informative.
 
17’s would be a step in the wrong direction. Most all tires in a 17 are load range E, they hare heavier and stiffer than 15’s. Heavier tires need power to turn them. You already know you lack extra power.
In your position, I’d get some 33x10.50R15’s and call it good.
 
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Thank you! This helps!

thsts exactly I was trying to find out 33x15 vs 33x17 (32 or 34 extended research) if it will make a difference.
 
If you want a less harsh ride...
You do NOT want Fox or Bilstein or Rancho 7000 (to name a few)

You want Skyjacker Bkack max or Rancho 5000x.
We install both here for customers with good feedback.

Back to your power.

Sonething is off here. Your description...or your Jeep.
My son has (I've owned a few myself with 31's) a 4 cylinder with 32's. He is running stock 4.10 gears. I razz him about that hot rod he's driving but even still he has no trouble hitting 77mph in it.
That said, if he hits a wheel chair ramp let alone a real hill without down shifting, it will drop 20 mph.
In other words the little 4 that could...can't...overcome much adversity like even slight hills without downshifting and or dropping 20mph before getting back to 70 plus 1 mile later.
🙄🙄🙄🙄

I'd say from your description of barely making it to 65mph...having 33's but with 5.13 gears...
65 should be no issue whatsoever.
Echoing again my son can hit 77 mph with 32's and 4.10 gears.

You've one inch bigger tire and have more weight but you also have a full ratio lower gearing(Numerically higher)

Something is off here....
 
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It's a 2.5 with 33s. You're lucky you can even make it to 55 MPH.

The 2.5 is simply not a good engine for highway travel.
 
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Rubicon88 said:
If you want a less harsh ride...
You do NOT want Fox or Bilstein or Rancho 7000 (to name a few)

You want Skyjacker Bkack max or Rancho 5000x.
We install both here for customers with good feedback.

Back to your power.

Sonething is off here. Your description...or your Jeep.
My son has (I've owned a few myself with 31's) a 4 cylinder with 32's. He is running stock 4.10 gears. I razz him about that hot rod he's driving but even still he has no trouble hitting 77mph in it.
That said, if he hits a wheel chair ramp let alone a real hill without down shifting, it will drop 20 mph.
In other words the little 4 that could...can't...overcome much adversity like even slight hills without downshifting and or dropping 20mph before getting back to 70 plus 1 mile later.
🙄🙄🙄🙄

I'd say from your description of barely making it to 65mph...having 33's but with 5.13 gears...
65 should be no issue whatsoever.
Echoing again my son can hit 77 mph with 32's and 4.10 gears.

You've one inch bigger tire and have more weight but you also have a full ratio lower gearing(Numerically higher)

Something is off here....
Click to expand...

thank you. I did read many articles here about Rancho 5000 and NOT to go with Rancho 7000. I will explore skyjacker.

yes I could barely make 65. She starts showing signs around 55 and struggles a lot every mph increase. Runs smooth on 45 mph.

it’s in garage because of losing coolant. I found foamish thing on the engine oil cap. The shop said it’s not head gasket leak but one of the radiator hose was leaking. That explains the loosing coolant but they are going to look into head gasket.
 
I have a 2.5 with 5.13 and 35s. Yes if I hit a hill I must down shift, but on relatively flat ground 70 is no issue. Heck I have had it over 80 before. You should not have any issue with 70. You also said it gets “scary”. Sounds like you may have some handling issues as well.
 
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Gollywomper said:
I have a 2.5 with 5.13 and 35s. Yes if I hit a hill I must down shift, but on relatively flat ground 70 is no issue. Heck I have had it over 80 before. You should not have any issue with 70. You also said it gets “scary”. Sounds like you may have some handling issues as well.
Click to expand...
I don’t think I could even touch 65, and you going 70 with 35’s?

is there any other things upgrades in yours?

yes. It’s scary because at 55-60 it waves like I’m in a boat. :)
 
I just put new tires on, also switched to aluminum wheels. The maxxis tires I run are 75is pounds. I didn’t notice much of a difference.
 
Don’t get me wrong, I’m not winning any races or anything and it may take a bit to get up to 70. But it will cruise at that speed on flat ground of course.
My brother in law has 33s and 4.88s and has no issues. We run about the same.
 
Gollywomper said:
Don’t get me wrong, I’m not winning any races or anything and it may take a bit to get up to 70. But it will cruise at that speed on flat ground of course.
My brother in law has 33s and 4.88s and has no issues. We run about the same.
Click to expand...
Thank you. I totally understand and I have been reading a lot. I tried it in TX straight freeway and flat grounds. No way it will even touch 65.

what tires did you end up getting?
 
What have you been shifting your engine RPM's at? I had a 2.5 with 4.88 gears & 33" tires. I'd been driving around with stock gears before that so I was really happy to get the 4.88 gears.
You have to be willing to REV the piss out of that 2.5 engine. With 5.13 gears you should be able to do 70MPH and higher no problem unless you are shifting into 5th at 40MPH. Figure out what is REALLY wrong before you start buying new tires and rims.
Even with 35" tires I could hit 70 MPH .

1619315744484.png
 
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Wildman said:
What have you been shifting your engine RPM's at? I had a 2.5 with 4.88 gears & 33" tires. I'd been driving around with stock gears before that so I was really happy to get the 4.88 gears.
You have to be willing to REV the piss out of that 2.5 engine. With 5.13 gears you should be able to do 70MPH and higher no problem unless you are shifting into 5th at 40MPH. Figure out what is REALLY wrong before you start buying new tires and rims.
Even with 35" tires I could hit 70 MPH .

View attachment 246555
Click to expand...
This is true. The 2.5 only makes 120HP and that peak is above 5K rpms. Max torque is about 3500 rpms.
 
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Gollywomper said:
This is true. The 2.5 only makes 120HP and that peak is above 5K rpms. Max torque is about 3500 rpms.
Click to expand...

I had no issues wrappin my 2.5 up to 5500 RPM's in 3rd to keep it up to freeway speeds climbing Snoqualmie Pass on I-90.

I never thought I was driving a pig of a rig but I came from driving a Samurai with a 1.3 in it so I wasn't lookin to win any races.
 
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