My 69 GS 400 is a low-option car--no power steering. Steering takes a toll on my arms, and on the steering wheel bolts. I am buying new tires for it, and I am thinking 70-series tires on 15" wheels up front. For Larry and the other tire gurus: Does cross sectional width significantly affect steering effort? In other words, will 215 70/15s be easier to turn than, say, 245 70/15s ? Enough to make a felt difference? Thanks P.S.-- I could convert to PS and will if I have to, but I hate trying to steer a PS car when its engine isn't running.
I had a manual steering 64 chevy and the best relief I got for the steering effort was to pump up the tire pressure. That car felt OK with the pressure about 40#s. I would think a smaller footprint (ie smaller tires) would also help. - Bill
X2, the 75 series tires would be easier on the arms than 70s, and pressure. But there's always a down side to any deviation from recommended tire pressure, over inflated tires wear more in the center instead of evenly across the tire. Considering the cost of tires today it would be hard to do that. Maybe just add power steering. Mike
Thanks to Bill and Mike for responding. If my engine wasn't so heavy, this would not be such a problem, but I can't afford to start all over with an aluminum block and heads. I guess upgrading to PS makes slightly more financial sense. Maybe I will give the 75's a try, and inflate them to max pressure, and see how hard it is to turn the beast. If it's still hard on the steering parts and on my rotator cuffs, then I will add PS.
In general, the wider the tire the more surface area that makes contact with the pavement. The greater surface area creates more friction and incrementally makes the wheel more difficult to turn at low or no forward speed. We have some early 60s 426 MOPARS with no PS. The steering wheels have a large diameter for a reason. Still, you must eat your Wheaties before you drive and parallel park one. p
Yes, stuff like parallel parking and 3-point turns is when it really gets to be a pain. I could handle it my younger days (I have owned this car since I was about 18), but the Wheaties don't help enough anymore, now that I am in my 50s. PS--I just found a handy tire height chart http://www.jekylhyderacing.com/HeightofTires.htm that tells you the diameter of any size tire. Now I can stop bugging Larry for this info when I have a question about it.
Here is a very handy site when changing tire sizes, that someone else posted before. I really like how it says how much your speedo may change. http://www.miata.net/garage/tirecalc.html
You can go to tire rack.com , search a tire, hit specs, it gives the specs on that tire and all the same tire in all its sizes. Tire rack is a good info tool, and fast. http://www.tirerack.com/tires/tires...ehicleSearch=false&fromCompare1=yes&tab=Specs
I can tell you section width will make the biggest difference on steering effort with no power steering. I drove a 94 Jeep Wrangler with no power steering for a long time without issue- sure parking lots and other low speed sharp turns could be a bit of a pain but not a huge deal. I then got the off road bug so went to a bigger tire - a 245/65 from the stock 225/75)- steering effort became much worse- did that for a year then stepped up to 35X12.5 tires and it was almost un-driveable. I put in power steering within a couple weeks of going to the 35" tires.
Our Nova is running 13x6 tires. I'd imagine a set of 15x6's would work nicely on the fronts of your car. I think the modern equivalent that we have is something in the order of 155/80's
Interesting. Do you use those front tires for cruising? Or just for racing? I think I saw a note on a wheel/tire seller's site saying that such a narrow setup should be for off-road only, so that made me stop considering anything more narrow than a 7 inch. Plus, I was having trouble finding wheel/tire combos in anything less than 215/70. I wanted to try 75 series tires for the front, but the dealers think that's an SUV application. Tire and wheel shopping is more complex than I thought it used to be, back in the days when I would just order the same standard size Radial T/A's front and rear.
It's the stock size for that car. The first gen Nova used a 13x6" rim and the wagons used a 13x6.5" rim. I run 215/70r15's on the Caprice since that's the stock size for that car with the 15x7" rim. I tried to steer without power steering on it before and it's doable, but not easy since the car weights in at 4,000 pounds and the modern style plastic wheel tends to flex a bit under heavy torque. I've found that anything less than a 215/70 tends to have a smaller rim diameter, but the 15's are out there if you look hard enough. What's the factory size for the car? We can run some numbers and find something that'll work.
Here's the info I found [TABLE] <TBODY>[TR] [TD]Standard tire size: [/TD] [TD]7.75 - 14 [/TD] [/TR] [TR] [TD]Tire width (mm): [/TD] [TD]197 [/TD] [/TR] [TR] [TD]Tire sidewall factor: [/TD] [TD]80 [/TD] [/TR] [TR] [TD]Rim size (in): [/TD] [TD]14 [/TD] [/TR] [TR] [TD]Total wheel diameter (mm / in): [/TD] [TD]671 / 26.4 [/TD] [/TR] </TBODY>[/TABLE]
Thanks! Last night I checked inside the glove compartment lid (that I think came from my '68) that said for GS 400, 7.75 - 14 is the correct tire. Tire Rack's site seems to think that any modern tire that size is a trailer tire only. It looks like the closest thing to original size that might be available from the radial passenger car tire makers, is 215 70 R15, which I think will work. The Mickeys in that size are within my price range. Thanks again for the help.
The Nova is getting 165R13's put on it. Now that's an odd tire size. Goodyear T-metric is the make if you need to try looking for the small tires. Your 7.75-14 converts to 205/75r14 or 215/70r14 (if you use the 205/75 as the base and want wide rears than you'd want to run 255/60r14 on the rears as it's almost the exact same as the 205/75) http://www.tirerack.com/tires/tiretech/45_conversionchart.html If you want to run really narrow than run 195/80r14. It's a fairly common size and would provide the least turning resistance. Just remember that it also has less grip when going through turns.
That is all great info. Thanks for providing it--I was having trouble figuring out the metric equivalents. One other complication I forgot about was tire running into header tube during hard turns. I may need one of those weird sizes, along with reverse backspaced front wheels, to keep from melting tire on header. Or, I can take credit for the invention of rubber-coated headers--the low-budget way to rust-proof your headers...
As for the header issue 1) Put the nose up on jack stands and turn the wheel all the way until you make contact 2) Measure from the inside of the rotor to the inside of the fender or frame. Doesn't really matter where as long as it's in a straight line and you remember exactly where the 2 spots are for the next step (maybe use a small piece of tape and place it on the 2 measuring points where the tape measure contacts metal) 3) Take the wheel off 4) Redo step 2 5) Subtract the 2 numbers to see how much more turning radius you have without the interference 6) Once you know how much further the wheel should turn you can figure out the difference in tire size or backspacing needed to achieve the goal You may find that you only have a fraction of an inch of extra movement, which may not be worth the added costs associated with fixing the problem.
Thanks. I think I understand that, and I will give it a try. My headers are a bit of a mystery, since they were installed in the early 70s and may not have been designed for a '69 GS. They are Hooker brand, but seem to be semi-customized (possibly modified BB Chevy headers?) and hence the interference issues.
