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Headers - Clearance Issues.... SUGGESTIONS?


TrunkMatt

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I run BF Goodrich 275/60 R15. Mounted on 8" rally's on the rear.

245/60 R15 front.

I also have a set for the Monte that are 255/60 R15 for all the way around.

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So right now I have 265/50 R15 Dunlop GT Qualifiers in the rear

and the 205/60 r15 in the front (same tire)

 

 

Rims are American racing torquelite wheels

REAR: 15x8 4 1/2 backspace

FRONT: 15x7 4 inch backspace

 

I am thinking up the rear to 275/60 and front to 235/60... most likely going to be a firestone wheel...

 

I like the wider back wheel look... went through the tires database you guys linked me to --- there are so many different setups my head is spinning.

 

 

 

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Hey Matt,

 

If it were me, I would 1st satisfy the ground clearance issues by selecting the tire that will get me the best front ground clearance without interference of tire rub on wheel wells & stance being the secondary concern. You are going to want as close to 4" clearance as you can reasonably get. The taller rear tires than front certainly will help the rake but it is going to be the fronts that will provide the bulk of needed clearance. Considering your running 8" rims on rear, not likely your going to swap from rear to front so, my take is to go as tall as practicle on front and then compensate on the rear with a tire size/tread width that gives the clearances & best stance. If you don't like the stance, you can always add stools under the rear coils to gain body lift for desired look. It is a fairly easy and inexpensive chore to do. Of course, this will probably stiffen the rear to some degree but if only 1/2 or 1" stools are needed, probably won't affect the ride that noticeably.

The other consideration is the effect the new tire diameters will have on your speedo accuracy in both speed & miles driven. Using a calculation that combines rear axle ratio to Tranny type to tire size will determine what driven gear you should be using and again is a relatively inexpensive fix. First would need to qualify speed-o-meter reading to see how accurate it is once you have selected and mounted new tires.

This is one of those things where one thing is changed, another is affected.

I would also say that your chassis to ground clearance does not look much different from mine, yet your clearance is certainly less. I'm no expert on Headers but, is it possible simply selecting a different set/style of Headers will resolve the problem? If so, there would not be any trade off as far as cost of tires vs. Headers. If you are in a crunch as the WM is so close then certainly the tires are going to be the quickest fix.

I've suffered through these same decisions with sometimes several different ways to go. Can be daunting at times when you don't know if you will get the desired effect/result. With me, I went with solving the problem 1st and then if warranted, tweaking it later. Frankly, I'm not satisfied yet and guess that is part of what makes it such a fun hobby, YOUR NEVER DONE! shock

 

just sayin,

 

p.s. What are the tire diameters now? Are those 60 series on rear and 50 series on front or is there a typo? Would'nt go less than 60 series with 70 series the optimum with 225/70R15 Front & 235/70R15 Rear. With your back spacing on rear, it would not affect your inside clearance but just maybe push the envelope for outside wheel well clearance with 8" rims.

 

Doug

 

 

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Not a type-o... they are 265/50 on the rear and 205/60 on the front. No idea why the previous owner set them up that way. I am guessing to keep Diameters similar despite tire width as that makes the rear tires 25.4 Diameter and the Front 24.7

 

As far as speed-o, it is reading about 7% too fast... When it says 60, Gps is saying 56.5

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Yeah, the shorter profile tires give the appearance of going faster/further than actual. Had that problem with mine before I timed the speedo & driven gear to actual conditions of car. Now I am so very very close to actual. If for nothing else than to not give the appearance of having been driven further than actual. When I first got her, had 60 series tires that were 215/60R15s front & 225/60R15s rear. When driving, seemed everybody except me were driving well above speed limit so made me suspicious. After using the mile markers to check, found I was showing 6.1 miles for every 5 miles actually driven.

Look, if your going to a tire dealership, just explain your problem and have them show you what you will gain in ground clearance at different tire sizes while retaining adequate tire/wheel well clearances. I'm not so sure you could'nt just peruse craigslist and find a set of used with wheels just short term until you get a better handle on the direction you want to go. If you like the tires you have, maybe looking for a set of Headers that may give you that needed clearance makes more sense to you.

Like I said earlier, there are a few options and a compressed period of time to resolve this issue before the WM. As the drive will be mostly Interstate to and from Meet, maybe it isn't all that important to solve it now. Regardeless, does'nt hurt to look around at some options/ideas.

Once you have decided on tire diameters and are satisfied, you can find out what speedo gear is in your tranny and do the calculation through TCI using tire diameters, rear axle ratio to determine what the driven gear tooth count should be to acurately calculate MPH and actual miles driven.

Always easier for the guy making the suggestions than the guy with the dilemma. Just stay focused on clearances and the best fit for your problem and go from there. I have learned that moving to quickly ofter creates head aches for me down the road. Anymore, if I'm not certain, I like to chew on it for awhile.

 

Doug

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It is amazing what new tires can do...

 

web.jpg

 

Now - before anyone says "NO NO NO!!! - CHINESE TIRE!!!" I know I know... itis intentional.

 

I decided to put on some cheaper tires that were the same size I want to move into to test feel and fit. I figure I'll run with these for a few months, and switch into the final more expensive tire later... or mess with spring and shocks and do something different. The proper tires are real investments, and these are a good "interim" tire to use before i make up my mind.

 

Besides, what's more American than something made in China?

 

Anyhow - the sizes are:

 

FRONT: 235/60 R15

REAR: 255/70 R15

 

I now have almost 4 inches to the headers - and I like the new more aggressive stance the bigger rears gave the car. Being a cheaper tire, these are a little more "bouncy" on the road -- but they are pretty quiet, and will give me a nice comfy ride to Boise.

 

Most importantly, the speed-o is not accurate.

 

 

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Looks real nice Matt,

 

Now I'm jealous sick. When I replaced my tires was'nt really thinking about the raised white letters and now wished I had mad! Really adds to the appearance.

You have the clearance and I think I've fixed my driver door problem. Handle seems to be holding but that spring clip looks to be a little fragile to me. Will check into it further once back from Boise.

Okay, looks like we are good to go! Got one more run to the store and finish the packing. Double check my list and can cruise until tomorrow morning for a different style of cruising.

looking forward meeting up tomorrow Matt. 9:30 AM still sound good?

 

Doug

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