Recommended tire inflation - Cordovans

[rojo_atlanta]

I bought a 1981 coupe last October, with a set of Cordovan Grand Prix Radial G/T tires on it. The size is P255/60R15. I checked with four retailers on recommended inflation, and got four answers: 35 lbs, 32 lbs, 36 lbs and 30 lbs.

I'm a computer consultant, so I'm not auto mechanics-savvy. I imagine the different inflations give you harder or softer rides. My objective would be longevity of the tire. Would you share your opinion for inflation on this tire, and the tradeoffs? I'm new to Corvette ownership and this forum, and both experiences have been terrific so far. I appreciate your advice!

 

[Jack]

WELCOME

red:
First, WELCOME to CACC! I seem to recall Cordovan as a lower price brand sold through some tire stores here in SC (maybe at Western Auto or the like?) ... don't recall an ad though in about 8-10 years. I'd try each of the pressures you've been told ... try them and see which one suits your driving style/comfort level. Also recall having a can of kiwi shoe polish ... color is cordovan.:Silly ... I had to do that!
JACK:gap

 

[maxrevs85]

I would recomend 35 psi......Most likely the max psi is 44......35 for handling and longevity , 32 for a little better ride. I prefer a harder pressure ,35. It gives better stability and less heat build up.

 

[Dave L.]

Tire pressure

I like your vette.It looks real sharp.I run 26psi frt and 24psi rear.Some guys I have heard run in the teens.Expiriment on your own.Different brands of tire will ride differently than others of course.

 

[maxrevs85]

IMHO, The tires of today are built for the least rolling resistance ,which produces better performance from the tire. I'm talking about performance from a safety and reliability standpoint. Safety should not be compromised for comfort. I havent heard of running pressures like 26 and 24psi since the late sixties ,unless your using a biasply polyglass tire. The 255 60 is considered to be a performance tire of sorts. The higher pressure gives sidewall stability with greatly enhances handling. If your going by the little sticker for recommended tire pressures on the older vettes ,they are very out dated. Remember ,this is a Vette ,not a Caddy. Comfortable ride and Corvette ? hmmmm I dont think so......

 

[page62]

Hey! I have the same tires on my '79...except they say "Mile Master" instead of "Cordovan"...everything else is identical.

I've seen a few tires in my time, and I'd say these are a pretty decent tire. They have a good UTQG rating (440AB). As a guess, I'd say they were made by Cooper or Kelly-Springfield. About the only thing wrong with them is they don't seem as "retro" as a set of Firestone Firehawks or Radial T/As.

Tire pressure? Low to mid 30's, depending on how you're driving. Low 30's for easygoing cruises, mid 30's for serious driving!

 

[JHL]

Rojo

The following is from the BFG site, but will most likely be typical for your size of tyre. For a 255/60 the maximum pressure recommended by BFG is 35psi.

As 255/60 was an option on your year of Vette it is entirely correct to consult the hand book or tags for the recommended pressures. Over inflation is as dangerous as under inflation particularly in the wet as the centre of the tread will bulge leaving less contact patch and if they have been run for a while like this a reduced tread depth in the centre due to excessive wear. A number of things need to be taken into consideration and I would only run high pressure if I was fully loaded and out for a high speed drive. Pressure will increase with heat and most if not all manufactures recommend checking pressure when cold. As the Vette has an almost 50/50 weight distribution front to rear and all your tyres are the same size you can run the same back and front. I usually run mine with 28psi.

Q. What is the proper air pressure for my tires?

A. Proper inflation is the single most important factor in tire care. The inflation pressure on the sidewall of the tire is the MAXIMUM operating pressure determined by the tire manufacturer. It is not necessarily the correct tire inflation for your vehicle. You should ALWAYS use the inflation recommended by the vehicle manufacturer.

You can find this information:

In your vehicle owner's manual, or

Posted on the inside edge of the driver's door or other door, or

On the inside of the glovebox door.

Always check inflation when tires are COLD, that is, when the vehicle has been driven less than a mile, or at least one hour or more after driving. Use a good quality tire pressure gauge. Note: It is natural for radial tires to have a slight bulge in the sidewall at their proper inflation pressure. Check inflation at least once a month, and before any long trip or before traveling with a heavy load. Always remember to check the spare tire. If your vehicle is equipped with a temporary or "mini-spare," check the sidewall markings for proper inflation pressure. It will differ from the inflation recommendation for your full-sized tires

*The dimensions shown are average values for tires measured on the specified measuring rim width. Individual tires may vary from data shown.
**Section width varies approximately 0.2” (5mm) for every 0.5” change in rim width. #WARNING: Serious or fatal injury may result from improper mounting, from underinflation or overloading,
or from tire damage due to abusive use. For proper mounting, see tire dealer. For proper operation, consult Tire Information Placard in vehicle. For high-speed driving, additional inflation pressure
and possibly reduced tire loading and/or upsizing is required. In the absence of specific recommendations by the vehicle manufacturer, use the following guidelines based on those in the
European Tyre and Rim Technical Organization Standards Manual. †For speeds over 100 mph, load and inflation MUST be adjusted according to the table below.
MAXIMUM SPEED mph 100 106 112
INFLATION INCREASE psi 0 1 2
LOAD CAPACITY (% of max) 100 100 100
Inflation pressure increase must not exceed the maximum pressure branded on the tire sidewall. When a consumer requests a replacement tire with a lower speed rating than the original
equipment tire, you must clearly communicate to him or her that the handling of the vehicle may be different and that its maximum speed capability is limited to that of the lowest speed rated
tire on the vehicle. Exceeding the lawful speed limit is neither recommended nor endorsed. Estimated data subject to change for all sizes.

I hope this is of some help.

Nice car by the way.
J.

 

[Dave L.]

Geez, I think I'll keep my tire pressures to my self next time.Somebody sounds a little out-of-sorts.ad

 

[maxrevs85]

Whoops , guess maybe it did sound a little overinflated.......sorry about that.

 

[page62]

Don't nobody take any criticism personally ... I don't!

Tire pressure is probably one of the most contentious issues out there. I always get a laugh when some bozo working at a "tire shop" tells me to put in 44 psi 'cuz that's what the tire says on it. I just ignore them and do what's right.

Bottom line: Don't overinflate, and for goodness sake don't underinflate...you don't want your tread to separate!

By the way, I did a little background research on those Cordovan/Multi-Mile tires. There's a pretty good chance (over 50%) they're made by Goodyear. In any case, having driven in the rain I'm pretty pleased with them.

 

[JHL]

I don`t doubt for a minute that modern ZR rated premium tyres are designed to operate at higher pressures but the 255/60 tyres found on older Vettes are not and are mostly SR rated.

One of the main things other than the revised suspension layout that made the C4 a better handling car than it`s predecesor was the tyres. They were far and away better than anything previously used on a Vette with a lower profile and a much more rigid carcass.

With only a few square inches of contact on each tyre it is probably one of the most critial componants of the whole car but the most overlooked. They should get the same regular checks as the rest of the car for pressure, cuts and nicks as failure can be life threatening.

J.