Novak Conversions Jeep Wrangler YJ shifters

Anyone Downsize Tires For Better Performance?

I have a 1994 2.5L with power steering. I took off the 31’s a few months ago and installed the smaller 29” tires (235/75/15). It was such a dramatic change in driving. The Jeep wants to go into 5th gear most of the time now. It rides and seems to handle better. It does great riding the trails on our land. The only downside is that it doesn’t look as good as it did because of my 2.5” lift. I’ll probably lower it one day. But, the smaller tires brought the 2.5l to life as expected and beyond. Cosmetics aside, major upgrade performance wise. Tires were have the price Goodyear Wrangler ATs than the BF Goodrich. I’d like to have both sizes honestly, but the 29” tires do very well for Street and riding in woods.
 
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It’s nice to see the experiences in this thread. These exact experiences are why a week ago, I purchased all stock suspension and will be putting it back to stock for practicality and handling. I’m undecided on factory 215/75R15 or larger 235/75R15, but either way I’m definitely ditching the 31” life and the lift. Excited about it.
 
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I actually did this once but to a tj. Put it back to stock with the small wheels and tires. It made a big difference in power (2.5) but at the end if the day I couldn't stand the way it looked and I ended up lifting it again.
 
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Its funny how so many lift and go big on tires based off looks. Yet when I had my 65 I never considered anything but stock type old school pizza cutter snow tires. IMO it was the way it was supposed to be and with that factory locked D44 and the gutless 4 banger it climbed like a mountain goat. I have to admit Ive lifted,modded and installed big rubber on more trucks and jeeps than I can recall and most of them I hated when it was dont due to lost performance, crap mileage and an drained bank account.
 
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Interesting conversation. I have a 1989 2.5 4cyl on BF KO2s as it's a Jurassic Park Jeep. Are you saying that my sluggish little buddy is because of the tyres and if I dropped down sizes the acceleration, consumption and ride quality might improve. As well as make it a bit faster??
 
jpjeep26uk said:
Interesting conversation. I have a 1989 2.5 4cyl on BF KO2s as it's a Jurassic Park Jeep. Are you saying that my sluggish little buddy is because of the tyres and if I dropped down sizes the acceleration, consumption and ride quality might improve. As well as make it a bit faster??
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That was certainly my experience. Big tires have a lot of rotational mass and changing the center of gravity does effect handling.
 
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Sunsport said:
That was certainly my experience. Big tires have a lot of rotational mass and changing the center of gravity does effect handling.
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I never thought about that. The mass. Of course. Little engine trying to turn those massive tyres, bound to be sluggish and take longer to get up to a decent speed. Good point. I'm stuck then, as to keep it looking like a Jurassic Parker I have to have the KO2s. Shame I can't find smaller tyres and put fake badges on the edge haha.
 
jpjeep26uk said:
I never thought about that. The mass. Of course. Little engine trying to turn those massive tyres, bound to be sluggish and take longer to get up to a decent speed. Good point. I'm stuck then, as to keep it looking like a Jurassic Parker I have to have the KO2s. Shame I can't find smaller tyres and put fake badges on the edge haha.
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Unless something changed, the 215/75R15 shown in some of your pictures shouldn't be causing hardly any additional sluggishness over the stock 205/75R15. It might be a bit more sluggish, but the reality is the 1989 TBI 4 cyl really just has very little get up and go in general. It would still be slow with bicycle tires.
 
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jpjeep26uk said:
I never thought about that. The mass. Of course. Little engine trying to turn those massive tyres, bound to be sluggish and take longer to get up to a decent speed. Good point. I'm stuck then, as to keep it looking like a Jurassic Parker I have to have the KO2s. Shame I can't find smaller tyres and put fake badges on the edge haha.
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Have you regeared the differentials?
 
machoheadgames said:
Unless something changed, the 215/75R15 shown in some of your pictures shouldn't be causing hardly any additional sluggishness over the stock 205/75R15. It might be a bit more sluggish, but the reality is the 1989 TBI 4 cyl really just has very little get up and go in general. It would still be slow with bicycle tires.
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Haha, yeah it's come close with byciclrs cutting me off. A few folks have said the same thing. It's just underpowered for such a heavy car. I'll just get used to driving miss daisy then.
 
Yep it came with these tyres and I have no history of any diff gear changes since 2001 when the UK records began. It was abroad for 13 years before that so it's anyone's guess as to what happened in those days haha.
 
I think it's just the 2.5. Never going to be a fast car by any means. It's probably lost some HPs over the years as well.

Not much to choose from over here and I probably should've done some more homework when I was buying as it's been a massive problem finding parts and trying to fix or replace parts. The 4 litre was much more popular.

I can't even source a dizzy in the UK as they are all 4 litre. Lesson learned.
 
I didn’t realize it was on 215’s!

Smaller tires and regearing won’t help that.

Maybe the motor has issues? Loss of compression? Timing is off? Clogged fuel filter? Clogged catalytic converter?
 
After driving my friend's 1990 2.5L many years ago, I can attest that they are very gutless. My guess would be that it's operating fine, but who knows. Hard to say without being there. The one I drove did have 30's which didn't help, but it would have still been super gutless had it gone back to stock.
 
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