Biggest tire size on a 78...

[joshs78sleeper]

Im getting new rims and tires this week and im trying to find out what the biggest tire size that will fit on a 78 is. Ive heard of guys putting 295's on the back and 255's on the front of some c3's without a problem. But im not sure if this was a 78. This is the setup I want to get. Id really like to have 295's on the back, and 255's on the front.

Im getting 17 inch torque thrust II's, What size profile should I get keeping speedo and everything in mind? How would 295/45/17's go in the back? What about the front?

Anybody who has put these tire sizes on a 78 or comparable year please let me know....or if you havent gone this big whats the biggest youve gotten on your 78?

 

[joshs78sleeper]

I forgot to ask....If i can fit 295's on the back...what size rim am i gonna need? Will 295's fit on a 17x8, 17x9?

 

[sscam69]

I think 265's in the back are the max w/o offset trailing arms. W/ the offset arms you have more to play with and then I think you can put those 295's.

I know someone around here did it.

What tires? Nittos, BFG DR, ET Streets?

 

[Vette 76]

Torque thrust 2's are great looking wheels.:cool . Good choice!! However, the larger diameter wheel you have the lower profile tire you will need to get under your fender wells. I am running 275/60/15 on rear, 255/60/15 on front on my 76. That is as large as I could get under the fender well. I am using stock 8" wheels(ralley) A 295 only comes in a 50 series profile in 15'' and will go outside of your fender well at least 1-1 1/2"

 

[Doug'sL81]

I have BFG T/A P265 50x15 all round on my 81 Vette

 

[joshs78sleeper]

Ok...So you got 275's on your 76 with the regular trailing arms? Is a 76 the same as a 78?

So basically i can fit 295's on with some offset trailing arms? How much is it gonna cost me to throw some offset trailing arms on?

I would probably be happy with 275's although 295's would be nice and help me to hook up better...

But Im getting my new rims and tires next week and im getting them at a very very good deal, so i need to figure out the biggest size i can throw on there.

Whats involved with installing offset trailing arms?

 

[sscam69]

www.c3sharktank.com

I think thats the address for Scott81's website. He's got some really well documented rebuilds along with trailing arms etc. That should give you a good idea about whats involved. And some other things you need to look into for the drivetrain, as this cars won't handle much power without things breaking.

What kind of resources do you have?

How much money do you have to throw at this car, if you don't mind me asking.

 

[joshs78sleeper]

Well its a limited budget right now. I already have the engine built, the rims and tires im getting next week for very cheap, and im having the trans completely rebuilt next week too. So I know the trans will be fine. Now I dont know about the rearend, and the rest of the drive train, lol....Im hoping it wont break for a while, because Im on a very limited budget right now.

It seems like it should be able to hold up to 400hp for a while. I mean some c3's came stock with 390 hp right? Anyways, i hope it lasts for a while with the new engine and tranny...eventually ill have enough to throw at suspension and rear end, but not yet.

Everything on the car was inspected and anything that needed fixing was fixed right before i got the car. My grandma had a fellow vette owner whos a mechanic go through everything. I have a big list along with reciepts of everything that was done.

 

[sscam69]

stock with 390 hp

Sorry bud, not the case. My 79 L-82 came with something like 210hp/275ftlbs and it topped out at 3K rpm. The seat of the pants feeling just completely died after that and the car was just making noise. Your 78 was probably close to that.

I had the engine rebuilt since then but still want more LOL. Looking into the XE268H from comp cams. I think it will a good cam to go with.

As far as the drivetrain is concerned you gonna have to do some beefing up, because it won't hold for long with that kind of power and constant thrashing. ESPECIALLY with sticky tires!!

I have already looked into it I was trying to go the same route as you.

 

[sscam69]

Oh and take it slow and leave some money for the "fudge factor" there is always one!!

 

[Twin_Turbo]

295's will fit on a 8" rim. 295's will also fit under the car, 275 will fit without relocating the e-brake bracket, the 295 may fit, maybe you have to move the bracket. It depends on how big the sidewalls stand out (on 295/60/15 you will have to mod it, I saw some 295/50/15's that didn't have to do it)

Marck

 

[Vette 76]

The 275/60/15 tires are Goodyear GTII and fit under my 76 with standard trailing arms. They don't rub on a 76 but it is a tight fit. sscam69 is right on everything he said. I have changed trailing arms on my 72 BB and it is a big deal if you intend to use your axle and parking brake components that can only be removed from your old trailing arms with the proper tools. I have a friend that owns a machine shop that built the tools for us both as he is restoring a 67 BB. If you use a hammer count on ruining your old trailing arms. sscam69 is also right about power differences. There is a major difference in the size of the half-shafts between my 72 BB and my 76 with 350. Best of luck to you! Vette 76

 

[joshs78sleeper]

Sorry bud, not the case. My 79 L-82 came with something like 210hp/275ftlbs and it topped out at 3K rpm. The seat of the pants feeling just completely died after that and the car was just making noise. Your 78 was probably close to that.

No...I know that the later c3's had nowhere near the same horsepower as like the 71 i think it was which came with 390hp stock. But i figured they used mostly the same drivetrain....but in assuming I may be wrong.

Is this the case or no? were the earlier c3's built to handle the power, but since the 78's lacked balls also lacked the drivetrain to withstand the power?

Like I said, im getting my tranny rebuilt and it will definitely be able to handle the power...but i dont know about the rearend and everything...

Oh, and Im going with 17" rims, so im thinking ill have to go with a lower profile...will a 295/45/17 fit under the car do you think?

Unfortunately i cant take the car in to see if it will fit...im getting an excellent deal on brand new rims and tires, but I have to just pick them up, and no return options...so hopefully when i come home with those 295's theyll fit, lol!!!

 

[Twin_Turbo]

There's a difference between net and gross Hp!!

Keep in minds that the later oens are measured with all the accessories on the engine.

 

[MLGower]

I've got 255/60-15 Goodyear T/A Radials on my 78 and the front does scrape when I make a real sharp turn. The back fits fine and I have the stock trailing arms. I haven't had any problems with it, as the scraping is very minor and only happens when I am in a real tight turn (parking lot).

Michael