Tyre Sizes: Maximum

[Azwol]

I'm currently running 235/60 15's front and 245/50 15's on the rear. I looking at running 295/50 15's on the rear. This is the size a lot of the Impala guys are running. I think they will fit in a BFG or a MasterCraft Avebger G/T. Anyone with any experience? What it the max size I can run? I have 7" cragar's on the front and 8" cragar's on the back.
And also, I'm loving the white letters out. What are your thoughts?

[Centurion717273]

I think standard sized tires, on chrome Buick wheels look rather nice. Standard wheelcovers and the optional wire wheelcovers look great also. After all that's what they where designed to have on them. Whitewalls really set these cars off, white letters make them look odd. The tires and wheels you list make the cars look cartoonish and loses the classic sportiness that the Centurion presents.

[Smartin]

I run 275/50/15 with my drag radials on an 8" wide wheel in the back. They look fine. I'm not sure about a 295, though. Is there a local tire shop that can give you advice on how wide you can go with an 8" wide wheel?

[Azwol]

Personally the 72 Centurion coupe I own looks a lot better in cragars 7" and 8" rears.
295's fit on an 8" rear rim. The rim isn't the issue, I wanted to know the max size that fits in the rear wheel well...
I looked on the v8buick site and a number of guys run up to 295" on the rears on cars like the GS455, etc without mods.
The impala guys run 295's. As a B body I think they would be alright. Has anyone done this on a Centurion?
And, sorry to the purists, but I'm taking off a lot of the chrome trims around the windows and wheel well etc. and the car is metalic grey, so white letter tires like the guys run on the v8buick site will look sweet. (ie: this is custom street machine so no need to talk classic looks).
Someone suggested 245's on the front but the 235's on the BFG's I run are max on my centurion.
What is the largest size anyone runs on the rears?

[Smartin]

I have 2" of extra space between the tire and the frame on my car with the 275's on it.

[dewbers]

Wow.... I am running 255/70/R15 on my ride as we speak. (letters out to the dismay of many on the board! LOL) I'd love to see what something bigger would look like. I wanted a nice meaty tire, but was afraid to go any bigger. Any pics of the cars you referrence in your thread?

Went back an uploaded some pics to show how they look, just in case you wanted to see them...

[EEE]

If Adam has 2" left to the frame with 275s, but is also on the limit with the backspacing (4"), on the outside, if I remeber reading correctly in another thread. Then if you would run a 295 tire, with a 5" backspaced tim, you would be real close to the inside, and have a little more left on the outside. Should theoretically be possible, no?

[Centurion717273]

I would have to wonder if the stock suspension is up to/built to handle the wider tires. The suspensions on these cars are designed and built to handle a specific size tire. Are you asking for premature suspension problems?
Why not get yourself a nice set of tractor trailer dualies and stick under there?

Maybe a set of them thar fancy mudflaps with chrome big boobed bimbo's would add to the look also.

[Azwol]

Thanks for everyones input. (except for Centurion717273 who still has something to say even if it is not constructive).
The tyre people I went to are very knowledge with this period of cars and do a lot of the chev, etc. work on cars from this period.
They said that shocks are nothing to do with it as with cragars and 295's the weight it is not much different from stock setup weight and the shock work load is actually less as the car rides a lot better with 255's etc and up. They laughed at the idea of "premature suspension problems" as the car is nearly 40 years old so the suspension is old already and the factory setup is hardly "cutting edge" and these 455's have more than enough torque to even notice the extra pull away power from stop of a more grippy setup.
I'll look at airsuspention or new shocks and springs in the near future.
If all the purists that run stock tyres could refrain from posting to this thread, as this thread is about max tyre sizes on stock diff and wheel wells. To help any purists that are still reading to logoff: I got rid of the vinyl roof on my hard top coupe
And Centruion717273: I'm not running 17" wheels like more and more people are running on B bodies. These are 15" rims with 50 profile height.
I actually know people running buicks with 315 rears on modified diffs and wheel wells.
Love the post from dewbers, letters out on our setups look awesome. If you go to v8buick and go to the thread on "what tyre and wheel combo's are you guys running?" there are some excellent pics of letter out coupes.
I've ordered 295's for the rear so can't wait until they arrive. I will then let you know how I go and back spacing sizes etc.
Thanks again for all the people that made a possitive contribution.

[Centurion717273]

I may have a different way of getting my point across, but the input is of importance and valid.

You are only fooling yourself if you buy into the information you received "They laughed at the idea of "premature suspension problems" as the car is nearly 40 years old so the suspension is old already and the factory setup is hardly "cutting edge"
Safety should be your first concern!!

I assume the knowledgeable people that gave you the "advise" are also the ones selling you the tires and wheels and wanting to do these downgrades to your car?

[centurion 455 ragtop]

Boobed Bimbo? I'll take that, in fact at my age I'll take small boobs too. Guys we all have to remember this site is somewhat different than others. Though we may and do have different tastes for these cars, we do and should respect that. On the flip side having the different views is also good. If everyone always agreed on everything in life, we would then all live a very boring life. The bottom line principle is that we are all preserving these cars in our own desired ways, which is a good thing.

My take on the topic of tire size, Yes in a sense the suspension is that of a 40 year old out dated technology. Whether you install huge 17 inch low profile tires and rims, or wide tires etc. We have to keep in mind a special word here: combination. As you you change one dynamic of the car you will no doubt effect other areas of the car. Wider or larger than factory recommended specs will do this. Its not the end of the world as other parts can be changed to accept this. Asking here is one place to go to for advise as this site is comprised of a bunch that show, cruise, race and have modified full size Buicks, mainly Centurions. Keep in mind what may apply to a GS or Riviera may not apply to the Centurion/LeSabre or Electra

I use to own a 1973 Riviera GS (boat tail rear) I was told no way, no how can you tow another car with it. The engine can handle it but the car design is not up to it. Well I proved it wrong as after installing a 3 series receiver I searched around and got an adjustable height hitch, We installed the receiver as far to the rear as possible and with the hitch was able to clear the pointed rear section of the car. Added polyurethane suspension bushings, a sway bar and air shocks along with a trans shift kit and cooling mods. I towed my GS for 6 years, total weight towing was around 5,000+ pounds, before selling it for my Centurion. I soon did the same with my Centurion.

What I am saying here is that anything is possible, ask here and we should all keep in mind to respect others on their likes and instead see if what is being asked is possible. These cars are amazingly simple in design and with some extra changes to the "combination" the modification usually can be had. Another example is a guy that has been on the V8 Buick Board running a Rivera boat tail on the Bonnieville Salt flats at speeds upward of 200 mph!

On installing a wider tire back spacing is important as with the clearance on your turning radius for the front tires. Also keep in mind the inside fender lip spacing. Try with your current tire installed measuring the side wall to the frame and the side wall to the inside fender lip. You will have to do some searching on the different back spacing on aftermarket rims. Also check on the Buick V8 Board and the Buick Performance Group site. Keep in mind some answers you get while helpful would not apply to your full size Buick. But don't over look them as it may point you in a right direction.

My Centurion I have installed a taller and wider tire but sorry she is all sealed up in a car bag for the winter, so I don't recall the tire size. The reason was I needed a tire to hold the extra load from towing. When I make a slow sharp turn I do rub ever so slightly on the inner fender well in the front. In two weeks I should be breaking her out for the season. As for extra mods for the larger tires and towing I rebuilt the suspension with all new bushings, shocks, and did add air shocks, only to help with the ride height when pulling, I don't like them but they work best. Also searched for some time and found a factory rear sway bar from Kimson who is on this board (thx Pal). I also had to foam coat and insulate the trailer receiver as I saw with a full gas tank while towing, the tank rubs slightly on the center part of the receiver (not a good thing)

[centurion 455 ragtop]

Forgot to ask, your reasons for the wider tires? Are you planning or occasional racing? Or just tooling around town with some stop light action? Either way keep in mind with a wider tire you will grab the road harder. You may very well get some wheel hop and put some strain on the u-joints and suspension and transmission. If your installing the wider tires for just looks and for cruising around town then skip the mods I suggested.

You may want to look into having the rear lower control arms boxed welded so they are more stable also a set of air bags which fit inside the coil springs. No need to over inflate them, just about 10-12 pounds in each. The airbags will stabilize the coil springs while under load. These two simple mods will prevent wheel hop and no doubt help with traction. Now once you do this the added stress is now placed on the driveshaft and u-joints. Good piece of mind and it doesn't break the bank is a good set of front and rear joints. No need for anything more unless you are looking to do some serious runs with the car. As you progress on ward into racing with more hp then you look into a trans shift kit, tranny cooler, different convertor, U-Joint girdle bolts, and a rear end girdle & studs (goes inside supporting the gears).

[dewbers]

[QUOTE=centurion 455 ragtop;10980]Boobed Bimbo? I'll take that, in fact at my age I'll take small boobs too. Guys we all have to remember this site is somewhat different than others. Though we may and do have different tastes for these cars, we do and should respect that. On the flip side having the different views is also good. If everyone always agreed on everything in life, we would then all live a very boring life. The bottom line principle is that we are all preserving these cars in our own desired ways, which is a good thing.
QUOTE]

Rick - you made a couple of very valid points on your post.

First, this one... Though we may and do have different tastes for these cars, we do and should respect that. On the flip side having the different views is also good. If everyone always agreed on everything in life, we would then all live a very boring life. The bottom line principle is that we are all preserving these cars in our own desired ways, which is a good thing.
Well said my friend. I have fun on this board with Bob and Phil and few other guys about my raised white letters. They don't love them... in fact, they've been pretty honest about hating them.
But, they've been respectful of my choices, as it's my car. As you said, the bottom line is that we all are preserving these beautiful cars, which is a VERY good thing!!

Your second point... Boobed Bimbo? I'll take that, in fact at my age I'll take small boobs too. Again, well said my friend! I've always been a fan of boobs... so if they are big, small or in between, who cares! There is nothing better than boobs... So just enjoy them!

You gents have a terrific day!

[73 Centurion]

Hello,

If I had the money I'd buy wider Buick style rims with increased offset. I'd put some wider tires, like the BFG, from the company that adds whitewalls to them. I think that would look sharp. I think the stock tires look a bit too skinny for the heft of our cars.

The wheel wells of our cars are cavernous. I believe there is one Centurion owner on here who is running 315's on eight inch Buick Rally wheels from a station wagon. The limitation is often not the size of the wheel wells but the offset of the rim. Most rims do not center the tire but place it closer to the outside. You'll probably need to increase the offset for 295's.

You can get width and height dimensions from the tire manufacturer. You could then create a cardboard template of the tire. If you use a simple disk in the middle you can get an exact measure of the offset required to fit a certain size tire in your car. Remember to leave some room for the axles lateral movement.

Here are a few points to consider:
1) If you fill the wheel well you'll need to control the axles side to side movement. Here are some of the things you can do.
a) Replace worn suspension bushings. Poly bushings limit lateral movement even more.
b) box the lower control arms
c) add a rear sway bar
2) Wider tires are harder to install. I have 235's and the axle must droop in order to get the tires in. This can be important if you're changing a flat. I don't trust bumper jacks, I think they are dangerously unstable. I carry a bottle jack made for a truck. It has enough extension to get the tire off the ground by raising the frame.
3) Be sure you carry the right lug nuts for your spare tire. The lug nuts for your Cragars may not be the right ones for a rally rim. It's good to develop the habit of checking the air pressure in your spare when you check the others.

Good luck and show us pictures of your results.

John

[Gum,beest]

Hi guys
I would like to put in my two cents on this topic and correct me when i am wrong but
I hear you guys talk about backspacing and the with of the wheel tub but i think the outside tire diameter is equally important
here are a couple simple rules i have learned
If you mount wider tires if you keep the center of your rim directly over the center of the axle bearing
That minimizes the wear of the bearing
And then the outside diameter of the wheel should be within 2% of the original
Otherwise you put extra strain on your transmission differential and engine
From factory the drive train is designed to run within a certain rpm range this is where the engine is at its strongest and give you the best fuel economy
I know that the engines we have are strong and beefy enough to overcome that and fuel economy is not an issue in the states but over here with current fuel cost of €1.52 for one liter it is ($7.80 per gallon)
besides that the speedo and Odo meter will not be accurate any more (and that can be an issue here as well we got speed traps every mile or so)

Having said that i like the look of fat rear tires
I run 235 all around at this moment but in the future like to go wider to ?
But not wider then the maximum for what the rally wheels allow