New tires & I am bummed big-time.....

JPhil

Huh?
Joined
Mar 26, 2008
Messages
1,361
Location
Loveland, Colorado, USA
Been running the 225/70-15 BFG TAs which were on the car when I got it. Monday I went and had new Firestone Firehawk Indy 500s put on. 255/60-15 in front, 275/60-15 in back. The 275s were special order. $600 all said & done.
First problem: turns out all my old stock wheels are bent, some worse than others, but all of them. Shit. Ordered up new wheels, $320 + tax. I'm not gonna mess with used wheels.
Second problem: The 275/60s are too tall. I did a lot of figuring & thinking before I ordered them and thought they would be OK. They spec out at 28" diammeter, only 1/2" taller than the BFG TA 225, and 1" wider on each side, so I figured that would be OK. Well with the 255/60s in front at 27", the rears are noticably larger. I guess I hadn't taken into account the wear on the old tires. Those 275s are so big in diameter (& width) that they will hit the fender lip. I have the back end jacked up to where it looks like shit. Like a farm tractor.
Third problem: On the way in to work this morning, something rubbed on a couple corners. Sounded like it was from the rear, but I will have look into it.
Forth problem: These tires follow rain grooves almost violently, jerking the car side to side enough to make you sea-sick. I still have 32 PSI in them to help them seat on the rims, perhaps when I let them down to 28 or 26 PSI it will get better, but I doubt it.......

I coulda spent $1500 and got new 17" wheels & tires, but I decided I didn't want to spend that kind of money right now, so I would just buy new tires and be done with it. Well I'm up to almost $1000 now, and if I have to eat these 275s and buy another pair of 255s, it will be $1250 and I'll still have 15' wheels & tires.....

I am very depressed right now.
 
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275s should fit the rear but it's tight on the inside.

Old photos: I had 275-60-15 on the rear and I even added a 1" thick adapter to clear the spring end and the trailing arm. It still did not rub the fender.

IM009904.jpg

IMG_6487cccCustom.jpg
 
Some P/O did flares on my '72, but the glass in there is thick as shit by feel, and so I assume it was just glued on top of the stock shape and filled in....

anyway, I have 275/59/17 Nitto in the rear and 255/50/17 on front, same wheel centerline as stock, it's CLOSE no doubt, a few weeks ago I dropped the spring to check the tire clearance, and it's only 3/8 inch or so....

but no evidence of it rubbing, driven over crappy streets daily....

:crutches:
 
I have the Firehawks on my 'Vette too. I do not have the rain groove problem you describe, but then again, there are no rain grooves in the roads around here. They ride hard and are good on dry roads but I do not like them in the rain. The combination of approximately 400 hp and a car that is light in the ass makes for squirrely wet weather driving. I also believe that the wider tires tend to hydroplane more.
 
My 'Vette will follow any ruts or grooves in the road and can be a handfull to keep on the road when that happens. It is especially noticeable on roads that have heavy commercial trucks (tractor trailers) cutting grooves in the asphalt. My front end checks out fine, all within tolerances. It is the wider tires that cause the car to wander. On a well maintained road I have no problems at all.

On the upside, if you ever go to the track you will find that the Firehawks will launch fairly hard and not slip unless you want them to.
 
OK so is it normal for "high performance tires" to follow rain grooves and jerk the car around? They feel great on un-grooved pavement.

Its not necessarily "high performance" tires that will do it. The wider the tire the more likely it is to wander on you. Also, I would check for slop in your steering system too. Mine would tend to wander a lot less after a steering box rebuild by gtr 1999
 
There's quiet a difference between 225-70 and 255-60. I'd expect the wider tire to be more 'sensitive' to road imperfections.

Did you find where the rear tires rub ??
 
OK so is it normal for "high performance tires" to follow rain grooves and jerk the car around? They feel great on un-grooved pavement.

Its not necessarily "high performance" tires that will do it. The wider the tire the more likely it is to wander on you. Also, I would check for slop in your steering system too. Mine would tend to wander a lot less after a steering box rebuild by gtr 1999

I also have a steering box built by Gary, well worth the investment. :cool:
 
OK so is it normal for "high performance tires" to follow rain grooves and jerk the car around? They feel great on un-grooved pavement.

Its not necessarily "high performance" tires that will do it. The wider the tire the more likely it is to wander on you. Also, I would check for slop in your steering system too. Mine would tend to wander a lot less after a steering box rebuild by gtr 1999

I also have a steering box built by Gary, well worth the investment. :cool:

YES, obviously, IF you are sticking with the stock system,.....but I still say it has limitations with modern rubber on the car...

a rack is one solution, apparently the Borgeson/Jeep box is another....I went rack in '02, not looked back....

;)
 
Day Two: Not so bad.....

Put it on the lift at the shop last night, could find no trace of rubbing anywhere on the tires or car. It has not done it since, even when I retraced my drive and took those corners a bit faster still.
I let the air pressure down from 32 to 28 PSI and that helped quite a bit. It still wanders on the rain grooves but not nearly as bad.
I think I will take off the 275s and put 255s on the back: I can feel a difference in the way the car handles with the back end jacked up like a cat in heat. It feels sloppier in back. The taller sidewalls probably also contribute to that.
My steering box feels good & all my steering gear feels tight, so I have not gotten into it. Suppose I should, huh? I've gone through most everything else.
 
I changed from 255-60 and 275-60 to 245-60 and 295-50..... Quiet a difference, still feels like riding on marshmallows but not as bad as the 275-60....

one day I'll get some 17" or 18"....
 
i always try to discourage you guys from putting a 275/60 on. A 275/50 would be just right. My 295/50s are mushy but look good on the car.

The indy tires are better than the BFGs but you never want to go to a taller sidewall. It does look like a tractor tire.
 
275/50/17 rear and 255/50/17 front, on '89 vette rims with 2.5" thick adapters....works fine '72 with mild flared by p/owner....

:bounce:
 
Day Two: Not so bad.....

Put it on the lift at the shop last night, could find no trace of rubbing anywhere on the tires or car. It has not done it since, even when I retraced my drive and took those corners a bit faster still.
I let the air pressure down from 32 to 28 PSI and that helped quite a bit. It still wanders on the rain grooves but not nearly as bad.
I think I will take off the 275s and put 255s on the back: I can feel a difference in the way the car handles with the back end jacked up like a cat in heat. It feels sloppier in back. The taller sidewalls probably also contribute to that.
My steering box feels good & all my steering gear feels tight, so I have not gotten into it. Suppose I should, huh? I've gone through most everything else.

If it ain't broke don't fix it. If everything feels good and passes a visual inspection and pushing and pulling on tie rods/ ball joints doesnt show you any kind of slop leave it alone. Also, look at the rag joint if it looks old might be worth replacing. Some people go with one of those solid type steering couplers that look like a universal joint. I might have used one if I knew about it when I replaced my rag joint.
 
Day five....My plan:

I ordered two new 255/60-15s for the rear. Hopefully next weekend they & the new wheels will be in & I'll get them installed. Then I will lower the back end down to where it should be.
I will take the 4 old BFG TAs and the four rims to one of the Mexican used-tire shops in Greeley and see if he'll give me $100 for all of them. The tires still have good tread, the wheels will be fine for a lowrider that takes corners at 10 MPH and never goes faster than 55.
I can sell the 275s to a hot-rod guy for $200, several people are interested.
I need to re-check the alignment anyway so I will probably add a bit of caster to the fronts and see if that helps to further reduce the rain-groove wander.

As it is right now, with the taller sidewalls of the 275s & raising the center of gravity in the back makes for really loose cornering: feels like a jiggling big-assed ho. It also changed the rear camber & front caster so it's twitchy.
My steering gear from the bottom of the box down is all new/rebuilt, and the box itself & column all feel really good so I won't mess with that.
The rubbing sound I have heard a couple more times, but now what I think it is is the spring bolts chafing in the t-arms or spring because I have the nuts run up so far to lift the body off the tires that the bolts are at an angle. Or something along those lines. I will see if it goes away when I get the car back to it's proper stance. (My front fender lip is at 27" off the ground, I had to jack the rear up from 28" to about 29 3/4")

I will post further developments & results as they come in.....
 
:nuts::nuts:One of my first trials as a new Vette owner was the appalling steering control. The 81 is over power steered in my opinion and the old tires just made it worse.

Since then, I've done a lot of suspension tuning and mounted Firestone Indy 500's in 255-60-15. Things are better now.

Point of this is, one of the first bits of advice I got was that the suspension was the same as they built in the 60's for bias ply tires so don't expect too much. I believe that. It can be so much better.

I guess that's why I'm on VetteMod...
 
:nuts::nuts:One of my first trials as a new Vette owner was the appalling steering control. The 81 is over power steered in my opinion and the old tires just made it worse.

Since then, I've done a lot of suspension tuning and mounted Firestone Indy 500's in 255-60-15. Things are better now.

Point of this is, one of the first bits of advice I got was that the suspension was the same as they built in the 60's for bias ply tires so don't expect too much. I believe that. It can be so much better.

I guess that's why I'm on VetteMod...

Well, besides road rut following, tramlining?, I found with more modern tires but only 17"x9.5 rims, it was greatly increased, and so wanted quicker steering ratio to boot....so went rack almost 8 years ago...had Borgeson been around with their recirc ball box, that's what I would have done....
12-1 steering is better than 16-1 buss driver's ratio anyday.....
 
big tires

Hey, Im new here.
Had 275's all around on my 80, no problems for two yrs, I sold it and bought a 95 conv. iv found out that you have to hang on to the c3's and can be tiring on a long drive but the c4 is like driving a caddie. one thing else i found is to have a 4 wheel alignment done at a good place.
 
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