first64riv Posted July 9, 2019 Share Posted July 9, 2019 Hey all, I've searched but nothing definitive. Will a 15x8 with 4.00" backspacing fit the rear wheel wells of a first gen? I would do 195 size tires. My hunch tells me this will fit. Chris Link to comment Share on other sites More sharing options...
NC1968Riviera Posted July 10, 2019 Share Posted July 10, 2019 I would think a good tire shop might have a wheel template device in which to test your theory. 1 Link to comment Share on other sites More sharing options...
steelman Posted July 10, 2019 Share Posted July 10, 2019 Short answer is yes, they will. Longer answer is you may have to rework the existing exhaust to get them to fit. Plenty of clearance for the wheel and tire, but sometimes the exhaust pipes want to take up this same space. Depending on where the muffler man put the pipes. "Look at all this room" doesn't work when you fill it with tire. 1 Link to comment Share on other sites More sharing options...
RivNut Posted July 10, 2019 Share Posted July 10, 2019 Why are you wanting to run 195 sized tire on a 8" rim? I have a set of 20" x 8.5" rims and a 255 tire on it pretty much stretches it to its limit. Link to comment Share on other sites More sharing options...
Barney Eaton Posted July 10, 2019 Share Posted July 10, 2019 Most tire people will agree that the tire and rim should be "paired" when it comes to width. The 15 X 8 size mentioned first......the 8 inch measurement is inside the rim bead. 8 = 203 mm If a 195 tire (7.68 inch) is installed on an 8 in rim the rim will extend past the tire rubber (look like a low-rider) If you are not aware, the 195 tire size/measurement is the width of the tire at the widest cross section. (not the tread width) Ed says he has 255 (10 inch) on 8.5 (216 mm) which gives him rubber past the rim .....that rubber protects the rim should you curb a tire. Also keep in mind that the 8 in measurement is the inside of the rim where the tire bead seats....there is about 1/2 inch on each rim flange, so if you measure the rim on the outside an 8 in will be about 9 inches. So in Ed's tire/rim combination he has about 1/4 inch of tire rubber extending past the rim on the front and back of the tire This does not answer your clearance questions, but is intended as input on choosing the tire for the rim. 1 Link to comment Share on other sites More sharing options...
awk409ak Posted July 10, 2019 Share Posted July 10, 2019 Isn't it more that the wheel will not fit over the drum. Not even speaking of tire size. Maybe I should state it this way. You should check to see if the wheel fit over the drum. I know for fact that my 15 x 7 's will not fit (4 5/16 BS) on my 64 Riviera. A wheel with 3 7/16 BS may fit, because that the stock rally wheel dimensions. I need to add a .875 spacer to make my wheel work. This is what I have seen. Art Link to comment Share on other sites More sharing options...
first64riv Posted July 10, 2019 Author Share Posted July 10, 2019 Thanks everyone! Link to comment Share on other sites More sharing options...
first64riv Posted July 10, 2019 Author Share Posted July 10, 2019 4 hours ago, Barney Eaton said: Most tire people will agree that the tire and rim should be "paired" when it comes to width. The 15 X 8 size mentioned first......the 8 inch measurement is inside the rim bead. 8 = 203 mm If a 195 tire (7.68 inch) is installed on an 8 in rim the rim will extend past the tire rubber (look like a low-rider) If you are not aware, the 195 tire size/measurement is the width of the tire at the widest cross section. (not the tread width) Ed says he has 255 (10 inch) on 8.5 (216 mm) which gives him rubber past the rim .....that rubber protects the rim should you curb a tire. Also keep in mind that the 8 in measurement is the inside of the rim where the tire bead seats....there is about 1/2 inch on each rim flange, so if you measure the rim on the outside an 8 in will be about 9 inches. So in Ed's tire/rim combination he has about 1/4 inch of tire rubber extending past the rim on the front and back of the tire This does not answer your clearance questions, but is intended as input on choosing the tire for the rim. Thank you for the input. I am aware of tire sizing. I threw out 195 because I am currently running 15x7 with a negative offset and I rubbed the fender well in the rear with a 195. I had to switch to a 185 tire. So with a x8 I could probably get away with at least a 195. My car is not a low rider. It's just lowered with Supremes. Funny you say that though because the wheels I found are Dayton wires. I'm only interested because they're on sale for a steal of a price. Thanks for the reply! Chris Link to comment Share on other sites More sharing options...
Barney Eaton Posted July 10, 2019 Share Posted July 10, 2019 Big wire wheel fan, so hope you can make them work. It might be worth having a tire mounted on one of the wire wheels and test it all around the car. Check clearances and that will help you decide what size tire you can use with the offset of the wires Link to comment Share on other sites More sharing options...
steelman Posted July 10, 2019 Share Posted July 10, 2019 Not sure why your 7" wheel rubs. Inside or outside face? Just as a comparison, I am running 255x55x17s on 8.5 wide wheels on my bagged 63 with no rub unless I set it really low. You may be rubbing exhaust on the inside of the tire. And when I set it down, it is the outside face that makes contact with the inner tub first. Link to comment Share on other sites More sharing options...
first64riv Posted July 10, 2019 Author Share Posted July 10, 2019 1 hour ago, Barney Eaton said: Big wire wheel fan, so hope you can make them work. It might be worth having a tire mounted on one of the wire wheels and test it all around the car. Check clearances and that will help you decide what size tire you can use with the offset of the wires I'm a bit of a wheel whore. I have a set of 5 1964 Wildcat wheels, a set of 5 Appliance Wire wheels, and the Supremes currently on my car. This is a pair of Dayton's that I want to pick up but I'm starting to realize the other accessories will make these wheels add up. They are brand new though....the struggle is real man!!! Thank you for your thoughtful replies. 8 minutes ago, steelman said: Not sure why your 7" wheel rubs. Inside or outside face? Just as a comparison, I am running 255x55x17s on 8.5 wide wheels on my bagged 63 with no rub unless I set it really low. You may be rubbing exhaust on the inside of the tire. And when I set it down, it is the outside face that makes contact with the inner tub first. I have the Truespoke Supremes in a 15x7 Reverse Backspace 1.75" or 57mm offset. That's the rub (so to speak). I had to bang the inner fender to stop the rubbing and get slimmer tires. Link to comment Share on other sites More sharing options...
awk409ak Posted July 11, 2019 Share Posted July 11, 2019 So what backspacing are you guys using on your 17 x 8.5 or 20 x 8.5? Art Link to comment Share on other sites More sharing options...
steelman Posted July 11, 2019 Share Posted July 11, 2019 9 hours ago, awk409ak said: So what backspacing are you guys using on your 17 x 8.5 or 20 x 8.5? Art 3 5/8 is the backspacing on my 17s. Link to comment Share on other sites More sharing options...
Barney Eaton Posted July 11, 2019 Share Posted July 11, 2019 Somewhere I read that before front wheel drive cars, most wheels had the hub mounting surface centered in the wheel. This equalized the wheel loading and made things simple. When front wheel drive vehicles came out, they wanted to make the drive shafts as long as possible so the outside bearing and hub was further out than rear wheel drive cars and the wheels had a big offset toward the outside (positive offset) the first Toronado is a good example. Now we have all these different wheel sizes, offsets, and widths that make selecting a wheel confusing but you do have many options to get the clearance you need. when selecting wheels......the first criteria is the bolt pattern that MUST match your vehicle, they you have wheel diameter (sometimes larger wheels are needed to clear the larger brakes you installed) wheel width, and offset..........then the easy part.....what design do you want. Link to comment Share on other sites More sharing options...
rapom Posted July 11, 2019 Share Posted July 11, 2019 (edited) Your combo will fit. My wheels are made by U.S. Wheel and are 15" x 8"'s with 4" backspacing (Bonus with this wheel is that the stock hub caps fit) and I have 295/55/15's in the rear and 255/60/15's in the front with no problems. The wheels even have divots to clear the front drum rivets. Had to do some slight clearancing for the front hub. All clearances are close in the back with the 2.25" exhaust pipes with some apparent rubbing at times that I never hear but can see when I take off the tires and see the shiny spot on the exhaust pipe. Even though there is over 1/2" clearance between the tire and the exhaust at rest. Must come from tight turns on inclines or declines. I have over 12,000 miles in 3 years on these wheels and tires. Edited July 11, 2019 by rapom Add picture (see edit history) 1 Link to comment Share on other sites More sharing options...
awk409ak Posted July 11, 2019 Share Posted July 11, 2019 Are running replacement drum then? Because I think factory drums are larger in diameter (the fins make the outside diameter of the drum larger). Art Link to comment Share on other sites More sharing options...
rapom Posted July 11, 2019 Share Posted July 11, 2019 (edited) I am running what appears to be the factory drums. Aluminum up front and cast iron in the rear. The drum fins look to be very close to the rim but still clear. I can take pictures if you want to see. I painted the front drums black where they would be seen through the wheels. Edited July 11, 2019 by rapom Add more content. (see edit history) Link to comment Share on other sites More sharing options...
awk409ak Posted July 11, 2019 Share Posted July 11, 2019 I'm not doubting you. I have the 15 x 7 rally's and they will not fit over my rear drums without using a .875 spacer, because the drum have fins on them. Art Link to comment Share on other sites More sharing options...
rapom Posted July 11, 2019 Share Posted July 11, 2019 Here are some pictures. Link to comment Share on other sites More sharing options...
rapom Posted July 11, 2019 Share Posted July 11, 2019 (edited) I know the 15x7 Chevy rallys have more backspacing than the 15x8 corvette rallys. Which doesn’t make sense but it is the case. Might be the same case with the Buick. Several friends of mine couldn’t fit the 15x7 rallys on their gm g bodies, because they would hit the rear frame rail with the tires installed. 15x8 rallys would solve the problem. It would appear from the pictures that any more than 4” of backspacing would hit the drum fins. Edited July 11, 2019 by rapom Add more content (see edit history) Link to comment Share on other sites More sharing options...
awk409ak Posted July 11, 2019 Share Posted July 11, 2019 Thanks. That must be it then a 4" BS seem to work. My 15 x 7 rallys are 4.312" BS. So they are too deep and hit the drum before the wheel mounting surface. I thought I was going to have to match what the 15 x 6 rally's BS is, which is 3.4375 by adding a spacer. I was thinking of the 15 x 6 with 225/70R15 on the front, rears would be 15 x 7 with 255/70R15. I'll have to try this wheel setup again. Thanks again for the help. Art Link to comment Share on other sites More sharing options...
rapom Posted July 11, 2019 Share Posted July 11, 2019 (edited) That should look good. You will have to use longer wheel studs if you use a spacer but you probably already know that. Edited July 11, 2019 by rapom Add content (see edit history) Link to comment Share on other sites More sharing options...
RivNut Posted July 12, 2019 Share Posted July 12, 2019 4 hours ago, rapom said: I am running what appears to be the factory drums. Aluminum up front and cast iron in the rear. The drum fins look to be very close to the rim but still clear. I can take pictures if you want to see. I painted the front drums black where they would be seen through the wheels. Painting cast aluminum will seal the pores in the metal. When the pores seal, because of painting or polishing, they loose their ability to cool. 😕 Link to comment Share on other sites More sharing options...
rapom Posted July 12, 2019 Share Posted July 12, 2019 Paint was very light, but I see your point. Link to comment Share on other sites More sharing options...
awk409ak Posted July 12, 2019 Share Posted July 12, 2019 Has anyone tried the rear replacement drums that Car Inc has for sale? Here's the link http://www.oldbuickparts.com/product_info.php?cPath=27_375_376&products_id=7039 Just wondering if there were any issues. They do not have the large fins and are smaller in outside diameter that will fit in the 15 x 7 wheel with 4.312 BS. Art Link to comment Share on other sites More sharing options...
jsgun Posted July 14, 2019 Share Posted July 14, 2019 On 7/11/2019 at 7:28 AM, rapom said: Your combo will fit. My wheels are made by U.S. Wheel and are 15" x 8"'s with 4" backspacing (Bonus with this wheel is that the stock hub caps fit) and I have 295/55/15's in the rear and 255/60/15's in the front with no problems. The wheels even have divots to clear the front drum rivets. Had to do some slight clearancing for the front hub. All clearances are close in the back with the 2.25" exhaust pipes with some apparent rubbing at times that I never hear but can see when I take off the tires and see the shiny spot on the exhaust pipe. Even though there is over 1/2" clearance between the tire and the exhaust at rest. Must come from tight turns on inclines or declines. I have over 12,000 miles in 3 years on these wheels and tires. That's some serious rubber. I was interested in some 15x8.5 torque thrust on CL, and used your car as inspiration. I chickened out, and went with some old 15x6 mags instead. Link to comment Share on other sites More sharing options...
jsgun Posted July 14, 2019 Share Posted July 14, 2019 Here's a wheel fitment calculator I ran across some time ago. Good for comparing stock to custom wheels. https://tiresize.com/wheel-offset-calculator/ Link to comment Share on other sites More sharing options...
awk409ak Posted July 15, 2019 Share Posted July 15, 2019 Jsgun, Thanks, nice link. I've alway went to the BF Goodrich site for tire sizes, better this is easier. I'm still suck on if there are any issues with using the Car Inc replacement rear drums on my 64 Riviera. If I use them I will not need to use spacers to fit the 15 x 7 Buick Rallys on the rear. The wheels will clear the outside diameter of the drums. Thanks, Art Link to comment Share on other sites More sharing options...
RivNut Posted July 15, 2019 Share Posted July 15, 2019 Cast ir9n is cast iron. As long as they fit every other place, bolt pattern, bolt hole diameter, center hole diameter, width, etc. you shouldn't have any problems. How do you know for sure your wheels will fit? Just because they don't show any fins in the illustration? Link to comment Share on other sites More sharing options...
awk409ak Posted July 15, 2019 Share Posted July 15, 2019 Hi Rivnut, Your right, I don't know for sure. I had called Cars Inc and had them measure the large diameter, which measured 14.375, I measured the ID of my wheel which is at least 14.625. Per the numbers it may work. I know that is still close, but before I ordered these drums I wanted to check to see if any members had any other issues with these drums. I know they are cast iron, but the factories were cast iron in the rears too, right? So should not be too much brake performance change. Just trying to figure out a way to mount these 15 x 7s Buick Rallys without a thick spacer and longer studs. According to Rapom, his wheels were 4.00 BS wheels and they fit (not Buick Rallys). My 15 x 7s are 4.312 BS, 15 x 6s are 3.4375 BS. Again this is ONLY in the rear. So if I can get the wheel over these drums without interference then I'm only looking at a spacer for tire clearance if needed. Let say I get these drum, I need to have them balanced, right? Would that be a auto machine shop that does this? If I'm missing something in all this, please let me know. All comments welcome. Thanks, Art Link to comment Share on other sites More sharing options...
RivNut Posted July 15, 2019 Share Posted July 15, 2019 (edited) I would be leaving the OE drums and using longer studs and a spacer. The new drums probably come from overseas and who knows what quality they are. The balancing question is something you seek an answer from CARS. Edited July 15, 2019 by RivNut (see edit history) Link to comment Share on other sites More sharing options...
awk409ak Posted July 16, 2019 Share Posted July 16, 2019 So to install longer studs, I would no doubt need to pull the rear axles, correct? Art Link to comment Share on other sites More sharing options...
RivNut Posted July 16, 2019 Share Posted July 16, 2019 (edited) That depends on the length of the stud and how much space there is between the back of the axle flange and the backing plate. Could be you could hammer the old ones out but the new ones would be too long to get back in. That would be a bummer deal. Perhaps someone else knows for sure. Are the 7" wheels the only ones you have or are you just in love with them 😍😍😍 Edited July 16, 2019 by RivNut (see edit history) Link to comment Share on other sites More sharing options...
awk409ak Posted July 16, 2019 Share Posted July 16, 2019 No no. I have the four so called Buick Wildcat rallys on the car now 15 x 6s. Looking to change all tires to redline and acquired two Buick station wagon rallys 15 x 7s for the rear. Would like to go with a wider tire on the rears. That's if I can make this work. Don't want to pull the axles. Like what you said " if not broken, don't fix it"😁😁 Art Link to comment Share on other sites More sharing options...
RivNut Posted July 16, 2019 Share Posted July 16, 2019 You can probably run the wider rear tire on the 6" rim and the ride and handling will be the same. Link to comment Share on other sites More sharing options...
RivNut Posted July 16, 2019 Share Posted July 16, 2019 I just went back and started reading from post #1. When I got to the pictures you posted, I took a look at the fins and how they interfered with the wheels. If you would, pull a wheel and post a picture of a complete drum. I've never seen a Buick rear drum whose fins stuck out beyond the drum itself. I'm curious to see if someone has not installed a set of 12 x 2 inch drums off of something other than a Buick. Those just do not look correct to me from what i can see. No matter what the offset, I would think you could get the 7" wheels to fit 9n Buick drums. I may be all wet, but someting doesn't look right. Link to comment Share on other sites More sharing options...
awk409ak Posted July 16, 2019 Share Posted July 16, 2019 Those pictures were of the front wheels and drums of Rapom's car. I'll get some pictures of the rear wheel and drums of mine this morning. Here the picture of mine as it is with the 15 x 6s. 1 Link to comment Share on other sites More sharing options...
awk409ak Posted July 16, 2019 Share Posted July 16, 2019 Three pictures of left rear Buick Rallys on the drums. Plenty of clearance as long as the BS (3.4375) does not increase. You can see the fins will make contact with the ID of the wheel. Third picture is my drum. Art Link to comment Share on other sites More sharing options...
awk409ak Posted July 16, 2019 Share Posted July 16, 2019 Here's the latest info. I made up four equally thick spacers with a 1/2-20 nut and washer measuring .556 from the drum surface. The wheel barely clears the drum on the inside. Leaves me about 6-7 thread on the studs. Not too comfortable with any of this. US Wheel Adapter will make me adapter, but .875 would be the minimum, these would bolt on. This would solve the the inside drum clearance, but does eat up outside tire clearance. Need to check more into this. Art Link to comment Share on other sites More sharing options...
rapom Posted July 16, 2019 Share Posted July 16, 2019 (edited) My rear drums also are cast iron and look like the ones just posted. Stockton wheels may be able to change the backspacing of your Buick wheels (depending on how they are made) as another option, but it would be pricer than wheel spacers. Edited July 16, 2019 by rapom Add content (see edit history) Link to comment Share on other sites More sharing options...
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