Rokus

Hey Guys,

I am a total newbie to this site and was hoping to find some help here. I recently replaced the stock tires with new Goodyear Silent Armor 33's on my 4-door Sahara with a manual transmission and ever since the car doesnt feel right. The car seems really sluggish and acceleration has really suffered. It's almost as if the first gear is too strong and accelerating from a stop is not smooth anymore, it feels really jerky and the engines revs up a lot. Do i need to install new gears? When I first got the car it was such a smooth ride and now its a bumpy, crappy, jerky jeep full of rattles.

Also, when I really push hard on the gas in first or second gear, this high-pitched rattle-like sound appears. Why?

I probably did a horrible job a explaning the issue but hope that someone out there may know what I am experiencing.

Thanks guys!

Robin
Long island, NY

nthinuf

Well, first off, you're going to get a whole lot of grief here for calling your jeep a car...

It is common to feel a loss of power when you increase tire height, and yes, putting in new gears is how you get back to 'stock' power.

For the harsh ride, my first thought would be tire pressure. Did the shop inflate them way up to 50lbs or so? Let a bunch of air out. 32 psi should be a good starting point, then adjust to your liking from there. (somewhere in the 28 to 35 psi range should be good for you.)

-Just noticed you have a Sahara, so stock was 32" tires with 3.73 gears? If so, there shouldn't be much difference at all in the performance or ride. You only went up one tire size...

Doc_D

There is a good chance the rattling sound you are hearing is pinging/detonation/knock. Most ECU's will pull a lot of ignition timing when this occurs which will put you down on horsepower.

While the larger tires will hurt your performance a little bit (but not much if you were already on 32" tires), it sounds like something else is going on. Did you change anything else besides the tires?

vegasoutlaw

Its amazing but this motor just doesnt have th HP to go up any in tire size. The auto is even worse. you dont say what your stock gears are but gearing is your solution for the loos of power

RedneckJeep

Sluggish after 33s with a manual? You must have 3.21s.

Comicnut25

I have 33s with my stock gears and mine has always been fine! It was barely going up a tire size and i dont think that should make that big of a difference! Did you install a lift with it? and did you put them on yourself or have it done? If you had all the tires and wheels installed go back!

scottrock

Also take into consideration the FBW throttle and ECU programming. It can take a few days for the computer to "learn" your shift/throttle habits with the bigger tires. My rig was sluggish the first few days I had my new tires but now it's much better. Still a slug with 3.21's but better than day one going from 29's to 33's.
I'm not sure about the jumping you describe though. That could be a tire out of balance if it is occuring at speed...

nclehmann

There's no reason for the loss of power and I think it may be unrelated to your increased tire size. Sahara's come stock with 32" tires and jumping up an inch isn't going to cause the sluggishness you are describing.

Keep in mind you changed from road tires to all-terrain tires. How wide are the tires? If they are 33/12.50s, did you install wheel spacers? Otherwise, did you replace the wheels? The tires could be rubbing against something. Do you smell burnt rubber? Have you visually inspected the inside sidewall of the tires for signs of unusual wear or rubbing?

Did you do any other work to your Jeep at the same time as having replaced the tires? Did you get an oil change? A differential oil change? Changed the air filter? Did you change the type or brand of gasoline you use? Did you add any heavy weight to the Jeep? Bumpers, skid plates, roof racks?

We need to rule out the most common factors that lead to this sluggishness. I can guarantee you that an inch increase in size did not do that.

Rokus

First of all, thank you for all the fast replies and I will make sure to refer to it as only a Jeep!

Besides the increased tire height, the new tires are a about an inch wider but I'm not getting any rubbing. , I haven't done anything to the car. Everything is stock. I do a lot of driving on beaches, do you think this could have something to do with it? Could the air filter be clogged up? I use regular gasoline (with ethanole).

I used to be amazed at how easy and smooth the jeep drove, even through New York City which is constant stop and go, ridiculuous potholes etc.... Now it's turnd into a major pain in my a.... - very uncomfortable, loud rattling from the window frame and acceleration is sluggish and the engine seems like its roaring. I love my jeep and it the perfect car for a fisherman who spents 90% in the great outdoors, but my car feel like I've had it for 5 years opposed to one.

I have a set of Spidertrax 1,5" wheel spacers I was planning on installing, will this worsen my problem?

First thing I will do later is take out some of the air pressure...

Mr.ZAP

Shitty gasoline can also lead to sluggishness and will make your engine knock...