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Discussion Starter #1
Been reading for a while and haven't seen an answer to my question yet. I'm in the process of measuring for some new 17's. Car is a 68 with Hotchkis and Bilstein all the way around. How much clearance should I be looking to maintain all the way around.

I have started on the rears. I am simulating a 275/40/17 on a 17 x 9.5 rim with 5.5" backspacing. I have about 0.75" between the rear of the tire and the inboard wheel house. I have about 2.5" clearance all the way around the diameter of the tire. The 2.5" seems like enough but how about the 0.75" to the inside?

Any thoughts on how much clearance to look for up front? Looking to go either 245/45/17 on 17x 8 with 4.75" BS. Might look at a 235/45/17 depending on fit.

I am trying to double and triple check as I will probably end up ordering custom made wheels to get the wheels I want in the sizes I need. I have Bear serious street disc brakes all the way around and am not sure what their effect on wheel position was so I'm measuring my application carefully.

For what it's worth, I'm currently running 235/60/15 all the way around on 15 x 7 YH rally wheels. I have a little rubbing up front on the top of the fender well right at the outside edge of the tire but should be able to smooth that out when I go to the new set up by raising the front end up 1/2 inch if necessary.

Murph


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I think you'll be fine if for no other reason than the thin/short sidewalls.
Whats the suspension ? mono ? multi ? coil-overs ?

Look in the tire/wheel combo thread for "what fits".
 

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Discussion Starter #4 (Edited)
Jeff - Me too. Doug is right that it should be a short pretty straight side wall so we will see.

Doug - Hotchkis 2" drop in front and 1.5" 3 leaf in the rear. Bilstein shocks on all 4 corners. I stayed with my mono shock plates but already know I will need to change those as I can see they will interfere. I have been reading all the fitment threads and that's how I ended up with the wheel and tire sizes I'm checking. I'm just trying to make sure there is nothing different about my car as once I order custom wheels there is no returning them.

Murph


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The answer to your question is so important and yet so difficult to get answered. I see you are going to use the set up recommended by DSE as the maximum.

In Mark Stielow's book Pro Touring he said he likes to leave 1/2-inch between tires and any hard parts. Of course his suspension is not stock.

When Driverzinc was in business their web site said for 65 series and higher to use 3/4-inch to the outer fender and 1-inch to the inner fender. For lower profile tires they said 1/2-inch to the outer fender and 3/4-inch to the inner fender was acceptable.

It would be awesome if people would report their measurements and let us know it they get any rubbing. Maybe you could be the first?
 

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One more source is Budnik's site. They say the following:

"When determining the inner clearance you should keep a few things in mind. On the front you will want to check tie rod ends, brake calipers, and of course full suspension travel. At the rear, your biggest concern on fat tire vehicles is to allow enough room for body roll and tire carcass shift. Generally, the taller the tire (70 series up to Pro Street), the more side wall flex is likely. Also remember that excessive body roll on cornering will reduce inner clearance, (usually 1" to 1 ½" of clearance is sufficient). Low profile tires, stiffer suspensions, and anti-roll (sway) bars will allow you a bit of extra width."

This seems to be inline with Driverzinc recommendations.
 

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Discussion Starter #7
Dave - you made me think of an important point here. Use!

The car will be almost 100% street driven. Might see the drag strip once or twice but will probably never be on a road race course. Now that I say those things you know what will happen. Never is an awful long time.

I would like to hear from people with similar combinations and how much clearance they have and if they have any issues.


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I have 275/40/17 on the rear with a 5.5 b/s 17 x 9.5 rim on my 69. On the inner I have 1/2" - 3/4" clearance. I get an occasional sidewall rub on the inner wheelhouse when entering or exiting a driveway curb cut at angle. I don't consider it to be an issue - just a small smooth shiny spot on the inner wheelhouse. Street only car.
 

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Dave - you made me think of an important point here. Use!

The car will be almost 100% street driven. Might see the drag strip once or twice but will probably never be on a road race course. Now that I say those things you know what will happen. Never is an awful long time.

I would like to hear from people with similar combinations and how much clearance they have and if they have any issues.


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Actually, as BPOS suggests, the biggest issues arise in street driving, particularly going up a driveway at an angle where the rear axle is sharply twisted as compared to the body.
 

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Discussion Starter #10
While I don't have a curb to get into my driveway, my dad does. Do you suppose I could simulate this by leaving one rear wheel on the ground and jack the other rear wheel up 4-6 inches and check the clearances like that?


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i thought that i should give this thread a bump, i asked this question 2 years ago with little response, why is this info such a big secret there is so much information shared on this site why are tire sizes and clearances such a big secret, the dimensions asked about would make it much easier for everyone to determin what back spacing they need to have but for some reason poeple don't want to give out this information, why ?

thanks tom
 

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Discussion Starter #12
OK. Did some more homework on the backs tonight. Front wheels are on and on the ground. I had the rear sitting up on jack stands with the wheels off. I jacked up one side while the other side remained on a stand. I was trying to simulate entering a driveway with a curb on an angle. I jacked it up 3" but also noticed the side on the stand went down by 1" so a total of 4" tilt on the axle. The gap went down from 3/4" on the inside to 1/4". I am measuring the tight side as the other side has 1" clearance when the axle was flat.

This weekend I'll pick up the multi-leaf shock plates so I can get the mono's off and make sure that the multi plates solve the shock interference on this wheel size.

Murph
 

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i thought that i should give this thread a bump, i asked this question 2 years ago with little response, why is this info such a big secret there is so much information shared on this site why are tire sizes and clearances such a big secret, the dimensions asked about would make it much easier for everyone to determin what back spacing they need to have but for some reason poeple don't want to give out this information, why ?

thanks tom
On my 69, 4 1/2 BS 275/60/15 MT ET Streets slight rub on inside tub when going up a drive on a 45 deg angle approx 2- 2 1/2 lowered rear.:thumbsup:
 

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Murph , I just went thru this as well with my 67, I wound up with 17" x 9-1/2" in rear with a 275/50r17 M&H drag radial. The front is a 17" x 7" with a 225/50r17 hankook ventus v12 tire. I am at stock hight front and rear. I have been driving about 60 miles now with no rub. The inside rear tire is about 3/4 to 7/8" to the inner well.I have not rubbed the outer lip either. I have been across several rurb like entrances with no problem. I have not encountered a 45* yet. But I dont see a problem if it did slightly because I would be moving slow slow and it would only be to the inner upper tire to wheel well. This would be a rare event for me. My rear is a multi leaf as well. I dont think I would tailor my rear tire set up for this rare event unless your drive at home is steep.

Sorry forgot to rear b/s. It is at 5.5" . The front is 4.5" b/s

The front has no rub at all. It does get close at the rear inner part of the tire to the subframe when you turn it lock to lock. But no problem.

My thoughts are you will have to consider how much you lower front and rear if at all. I believe you will be fine with the inner well on the rear with the 17x9.5 5.5 b/s. Just choose your tire wisley. You can look up the tire size on M&H web site to see what I have.

I also only street drive my car as well. And do plan on taking it to the dragstrip. Mostly street. I dont see any problems at all.
 

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Discussion Starter #16
I have 275/40/17 on the rear with a 5.5 b/s 17 x 9.5 rim on my 69. On the inner I have 1/2" - 3/4" clearance. I get an occasional sidewall rub on the inner wheelhouse when entering or exiting a driveway curb cut at angle. I don't consider it to be an issue - just a small smooth shiny spot on the inner wheelhouse. Street only car.
Hey Al - Just looked at the pic in the link shown in your signature. Nice looking car. What wheels are those. They are similar to what I am looking for other than I am looking for gloss black centers.

Murph
 

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Discussion Starter #17
I want to keep this thread up to date but my progress has been slow.

I finally got the rear shock plates changed and the rear shock lower studs converted. I bought the repro multi leaf plates from D&R and drilled them out for the 1/2" u-bolts. Installed them and the shock mounting surface angle wasn't even close. An at home effort to try to bend them an additional 5 degrees was fruitless. I bit the bullet and purchased a set of the DSE plates. Drilled them out for the larger u-bolts and they fit perfect. I should have just listened to everything I read and purchased them first.

The lower shock bushing and steel sleeve on the Bilstien lower mount also proved to be a pain in the as....... The general info suggested I should be able to press the steel sleeve out of the bushing. We'll let me tell you, that wasn't going to happen. I ended up being able to press the bushing and sleeve combo out and then found some new lower bushings that didn't have the sleeve in them.

So now on the lowers I have the clearance I need to run the 17" wheels I need to the lower shock mount. I run rear disc brakes and have 6.5" clearance from the mounting surface to the inner fender well on both sides.

Murph
 

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Discussion Starter #18
Murph , I just went thru this as well with my 67, I wound up with 17" x 9-1/2" in rear with a 275/50r17 M&H drag radial. The front is a 17" x 7" with a 225/50r17 hankook ventus v12 tire. I am at stock hight front and rear. I have been driving about 60 miles now with no rub. The inside rear tire is about 3/4 to 7/8" to the inner well.I have not rubbed the outer lip either. I have been across several rurb like entrances with no problem. I have not encountered a 45* yet. But I dont see a problem if it did slightly because I would be moving slow slow and it would only be to the inner upper tire to wheel well. This would be a rare event for me. My rear is a multi leaf as well. I dont think I would tailor my rear tire set up for this rare event unless your drive at home is steep.

Sorry forgot to rear b/s. It is at 5.5" . The front is 4.5" b/s

The front has no rub at all. It does get close at the rear inner part of the tire to the subframe when you turn it lock to lock. But no problem.

My thoughts are you will have to consider how much you lower front and rear if at all. I believe you will be fine with the inner well on the rear with the 17x9.5 5.5 b/s. Just choose your tire wisley. You can look up the tire size on M&H web site to see what I have.

I also only street drive my car as well. And do plan on taking it to the dragstrip. Mostly street. I dont see any problems at all.
JB - that's great info thanks. Do you have the stock rear end and are you running rear drums or rear discs?

Murph
 

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Hey Al - Just looked at the pic in the link shown in your signature. Nice looking car. What wheels are those. They are similar to what I am looking for other than I am looking for gloss black centers.

Murph
Thanks - Just saw this. The wheels are pre-China American Racing CL205. Same as a TT2 but with painted(powdercoated?) centers. 17x8 & 17x9.5
 

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JB - that's great info thanks. Do you have the stock rear end and are you running rear drums or rear discs?

Murph
I have stock rear multi leaf spring with a disc conversion from the right stuff company. I could not imagine the disc thickness would be 1/16" more than the drum when it is mounted to the axle.

Also just a note, My inner lip is not rolled. It is stock. I thought I would have to contend with it , but I have not had any problem. If more outer fender clearence is needed it could be rolled to give aprox 1/2" to 5/8". Again , this is all based of my stock set up.

Sound like you are getting there.
 
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