Anyone with a 318 and 3.55 gears change from 25" tires to 28" ?

[shadango]

I am struggling with trying to decide on tire sizes for my car. 

Figured I would try and see if anyone had the same setup as me and could provide feedback.  I have been hijacking another thread and am starting to feel guilty...LOL   

So thought I would start a separate thread.  I also figured that if I could find someone who has the same setup as me it would be apples to apples....

I have a 318 (tweaked and runs good, especially up top)......3.55 rear end (recently changed from 2.76s).....727 tranny.  The 3.55s woke up the car.

Currently running rear tires that are a shade over 25" tall, almost worn out. (235/60/15, supposed to be 26" tall , I guess they are when new)

8" rim in the back, 4.5" backspace

Interested in going to 255 (27") or 275/60/15 (28") in the rear.

I want a meatier looking tire to fill up the wheel wells a little better (I have an add-a-leaf increasing the rear height which is actually tad high for my tastes)......also want a little better ride (have 1" t bars and the add-a-leafs, so I was thinking a little more sidewall would help)


Front tires are currently 195/65/15......not sure what tire size to go for there.....seems people like the 235/60/15 in the front....but that seems wide compared to what I have now...

Hoping for feedback from fellow 318 or 340 owners that may have a similar setup.

7 inch rim, 4" backspace.

The plan is to crank up the t-bars in the front a little and somehow drop the back end an inch......somehow...LOL

Car as it sits right now....



Thanks for any and all feedback!!

[burdar]

235's in the front will look really good.  255's in back would look really good too.  I'd say the 255's would be the minimum size for the rear. 

The main thing that needs attension is how high the back end is sitting now.   It's way too high.   Adding a bigger diameter tire in the back will raise the back up even more.  I think you could accually take out the extra leaf....go to a bigger tire, and have the look you want.

[Strawdawg]

You can find a formula and work it out...but there is about a 9% difference in the tire sizes..and the car will feel more like 3.23 gears when the effective gearing is taken into account

[shadango]

235's in the front will look really good.  255's in back would look really good too.  I'd say the 255's would be the minimum size for the rear. 

The main thing that needs attension is how high the back end is sitting now.   It's way too high.   Adding a bigger diameter tire in the back will raise the back up even more.  I think you could accually take out the extra leaf....go to a bigger tire, and have the look you want.

I think my front end is actually lower than it normally would be.....will be raising it up a tad to allow for the bigger fronts (whatever size I end up with) and the sidewall of the front will also be a little taller......as will the rear......I am thinking the net change wont be TOO much higher in the back.....provided I go bigger in front as well as the back.

When you say "extra leaf".....do you mean the half leaf?    I already have that out. 

The add-a-leaf I am referring to I installed to fix saggy stock springs, with the plan to go to "real" springs later.....but the more I read about spring choices, I am not convinced of the right way for that yet....so I was figuring I could  swap the new tires in and then see where things stand (sit) and then decide.

....wondering if I shouldnt have gone with 3.91 to start with......

As it is, maybe I will split the diff and go 255 in the rear if the 275 would be a 9% reversion back to my old gears....   

[Moparal]

Shadango,  trust me, the 355's are and were a good choice. Especially if you run the 275/60/15   , they are not 28 inches tall anyways. More like 27.5.   With your gears and the 275's you will like it just fine. RPM'S will be good for all around.  I did the same set up on my cuda and used 235's in the front.  Then these are the guys I bought my springs from. The ride height was just right, as you have seen pics of my purple car posted before. The add says approx 2 inches, but it was around an inch after it settled.


http://cgi.ebay.com/ebaymotors/REAR-LEAF-SPRINGS-70-73-CUDA-CHALLENGER-2-LIFT-_W0QQcmdZViewItemQQhashZitem519091af82QQitemZ350317817730QQptZVintageQ5fCarQ5fTruckQ5fPartsQ5fAccessories

[shadango]

Shadango,  trust me, the 355's are and were a good choice. Especially if you run the 275/60/15   , they are not 28 inches tall anyways. More like 27.5.   With your gears and the 275's you will like it just fine. RPM'S will be good for all around.  I did the same set up on my cuda and used 235's in the front.  Then these are the guys I bought my springs from. The ride height was just right, as you have seen pics of my purple car posted before. The add says approx 2 inches, but it was around an inch after it settled.


http://cgi.ebay.com/ebaymotors/REAR-LEAF-SPRINGS-70-73-CUDA-CHALLENGER-2-LIFT-_W0QQcmdZViewItemQQhashZitem519091af82QQitemZ350317817730QQptZVintageQ5fCarQ5fTruckQ5fPartsQ5fAccessories

Well, as you know I think about stuff waaaaaay too much.  LOL

Just dont want to spend the bucks on tires that I will hate or that will take me backwards toward 2.76 again.....   I guess I can always try the, and then swap back out of need be.

I actually like the 3.55s with the tires I have around town.....highway is around 3k at 60 or so which is higher than I am used to, so losing 200 rpm wouldnt kill me....

For the springs, you ended up with 1" higher than stock, but what is stock....level?  I like more rake......what i have now is more than I would prefer but i dont hate it......not sure if 1" will do it for me....I know that the car will handle better if leveled out, but it doesnt handle terrible now.....corners good and such....doesnt drive funny like some have said....I just like the look of some rake.....Was considering super stocks, but some say that one side is higher than the other and that would drive me nuts....

[Moparal]

When I was finished, I had 27.5 height in the center of the back wheel lip and 26.5 in the center of the frnt fender wheel lip

[shadango]

When I was finished, I had 27.5 height in the center of the back wheel lip and 26.5 in the center of the frnt fender wheel lip

I have 28 3/4" at the rear and 25 1/4" at the front.....so right there, you can see my front is too low.....and that probably makes the rake more than it should be even with the add a leafs.

That assumes that our fenders are the same, etc.

[Strawdawg]

It is all taste, and intended use, I think....   I am more into handling....I forgot what my car was setting after installing the hotchkis springs...seems like it was a hair under 26" in the rear....engine is out now so I cannot  remeasure for awhile.

To me, I would say your front was about right and the rear is way high....

[Road_Runner]

I went with the 235/60 on 15x7 ralleys on front & 275/60 on 15x8 ralleys on back based on  recommendations here and could not be happier with how the Barracuda looks & rides.  But the taller rear tires definitely hurt acceleration with the stock rear gear.  I've been going back & forth between either going to a 3.23 or 3.55 if I don't add some kind of o/d and a 3.91 if I do.  So for me, your 3.55 should be about ideal with the 318 and like you I'm staying with the original 318 for now but may go to a 340 later if I think I need to after driving it for a while.  I'd like to think I can get to 350-375 hp with the 318 and that that would be plenty to make me happy.  We'll see, but I couldn't be happier with the wheels & tires and don't think I'll be changing them.

Later, Jim

[shadango]

I went with the 235/60 on 15x7 ralleys on front & 275/60 on 15x8 ralleys on back based on  recommendations here and could not be happier with how the Barracuda looks & rides.  But the taller rear tires definitely hurt acceleration with the stock rear gear.  I've been going back & forth between either going to a 3.23 or 3.55 if I don't add some kind of o/d and a 3.91 if I do.  So for me, your 3.55 should be about ideal with the 318 and like you I'm staying with the original 318 for now but may go to a 340 later if I think I need to after driving it for a while.  I'd like to think I can get to 350-375 hp with the 318 and that that would be plenty to make me happy.  We'll see, but I couldn't be happier with the wheels & tires and don't think I'll be changing them.

Later, Jim

Thanks Jim

What gears you have out back?  Guessing 2.76s.....

Thats what I had before, and I loved how the 3.55s woke up the car.

I guess one key issue on my side is that I also have a purple cam in my 318...no idea what specs, but given the lack of vacuum at idle , the rough idle and how the power turns on at high rpms, its an older "high rpm" grind.....so my low end (while definately improved since the gear change) isnt stellar.hence the concern about going too big in the back.

I have been thinking maybe this fall/winter I wiill consider swapping out the cam for something more modern and a little more friendly down low....

But yeah, I keep leaning to the 275s......with the 255 a possibility.

 I just STILL cannot get over the concept that the rear tires I have now (which seem wide to me) will work on the front, but everyone says they will.....how do the 235s affect steering , if at all, being wider?

[Tonefiend]

I'll have to see what tires I have.  3.55 - 318 - 15" rims

[HP2]

Is there anybody local to you that would let you borrow their tire/rim set up to try one of the other? Are you affiliated with the local mopar club? Given the popularity of 255 and 275 combos, I'd think there is someone close by you could swap on a set and let you try them just to put you rmind at ease about the difference.

[vinb]

I have 275/60/15's on a 8" wheel, they are 27.9" high and 89" round.

With my 3.55 gear and a 4spd it's 2750 rpm at 66 mph, with the automatic trans it was 250 rpm higher..

The front tires are 225/70/15 on a 7" wheel  26.1" high  and 86.5" round..

[shadango]

Using the calculator, it looks like if I go with the 275s in the back it will be the same as keeping my 235s and going to a 3.32 gear.

That seems like that would be a minimal loss at the low end, right?

255s would be like keeping the 235s and having 3.43 gears....probably a better fit if i want to keep the current performance (which I do)....but using the charts, seems like the 255 wouldn't have the meaty look I would like......only an extra 1/2" sidewall and only 3/4" wider....the 275 has 1.57 inches more width and almost 1.5" more sidewall.

That is all based on getting the same RPM for a given tire size, at 65 mph.

Am I correct in figuring it this way?