What Tire pressure should I use in my new auto tires????

[Reacher68]

And THAT's why the traction (& tread life) on your Yokohama Advan Fleva v701 205/55 R15 has been so poor, as you've mentioned elsewhere! The Yoko was designed with the capability to carry a car weighing in at over twice the weight of your Spyder's rear end when run @ 28psi, so with half the weight on it, at 28 psi the Yoko was grossly over-inflated, giving you the wear pattern you've shown us; it would never get its tread up to operating temperature (which effectively requires about a 3-4 psi increase in pressure from cold after an hour's riding & you would've had very little pressure increase at all, if any!) so it'd never provide its best possible traction; it would've given you a much harsher ride; it would've been far more rigid than ideal to keep the tread firmly in contact with the road all the time; it would've exposed your tire to excessive wear (particularly in the middle of the tread, only due to over-inflation rather than 'throwing-out' like the OEM Kendas); and the list goes on!

It's the air (& pressure) inside the tire that carries the load on it, and your Spyder is a much lighter load/weight than that of the cars that need 28 psi in that Yoko to carry their weight, so you need less pressure in it to carry the load - and by over-inflating it for the load the way you did may well have given you a very direct & precise feel with little sidewall roll, but Radial Tires are DESIGNED to have a fair degree of sidewall roll in order to keep their tread surface firmly in contact with the road surface.... that's the big difference between radial & cross-ply tires & how come radials improved ride & handling while significantly increasing traction - only your radial Yoko wouldn't have been able to keep its tread firmly in contact with the road surface, cos the sidewalls that've been made strong enough to carry a heavier load couldn't flex enough at that pressure so it would've forced then to 'lean' rather than flex & you would've been peeling the inside edge of the tread up so that you were running around the corners on the edge of the tread (& probably wearing the tread shoulders 'round' too! ) So yeah, you might find the ride different once you start running your rear tire at a pressure 'more appropriate for the lighter load', but by running the Yoko at a 'more appropriate for the load' pressure of 18 psi, the Yoko should be able to perform EXACTLY the way it's designed to, instead of riding & gripping the road like a brick in the manner it would've at 28 psi under a Spyder!

But I really don't want to type all the rest of this out again - there's a heap of info already on the Forum about this, it'd pay you to do a bit of searching & spend some time reading it; and reading the reports by many on what must by now add up to literally millions of miles successfully run by the collected members on these 'more appropriate for the lighter load' lower pressures - Go on, you know you want to, and you might learn something too?!

How times have changed. When I was researching this 3.5 years ago, it seemed common and agreed that a 28psi rear was okay and preferred. Frankly, after I got the new tires I fell off the forums and have only looked on rare occasions. As I am doing new research for a new tire, I am finding exactly what you said above to be true and that less traction and obvious center tire wear resulted from my over-inflation. (Notice I have been just responding to threads I was reading and didn't actually post a new thread about tires ) At this point, I'll pick a new rear and work on having it inflated properly. I am leaning to the Vreds just because my fronts have been great. I am wondering if I would notice any handling difference from a Vred at 205/60 to a General or Kuhmo 215/60 provided they are properly inflated this time.

[BLUEKNIGHT911]

How times have changed. When I was researching this 3.5 years ago, it seemed common and agreed that a 28psi rear was okay and preferred. Frankly, after I got the new tires I fell off the forums and have only looked on rare occasions. As I am doing new research for a new tire, I am finding exactly what you said above to be true and that less traction and obvious center tire wear resulted from my over-inflation. (Notice I have been just responding to threads I was reading and didn't actually post a new thread about tires ) At this point, I'll pick a new rear and work on having it inflated properly. I am leaning to the Vreds just because my fronts have been great. I am wondering if I would notice any handling difference from a Vred at 205/60 to a General or Kuhmo 215/60 provided they are properly inflated this time.

In reality "common psi's of 28" were for Kenda tires ONLY ...... Auto tires are Very different ....Peter and I have been trying for almost a decade to convince folks as to the Science of proper inflation ..... Mike

[Reacher68]

In reality " common psi's of 28 )" were for Kenda tires ONLY ...... Auto tires are Very different ....Peter and I have been trying for almost a decade to convince folks as to the Science of proper inflation ..... Mike

I didn't pay enough attention I guess.

[Peteoz]

I didn't pay enough attention I guess.

No, it wasn’t a case of not paying attention, Reacher. So many of those responding do not take the time to see that the thread to which to which they are replying is about aftermarket car tyres, and comment that they are running at 16 and 28. Unfortunately, they are in fact referring to their Kenda tyres, but don’t reference that in their response. That is where a great deal of the confusion arises.

There’s an interesting FB post doing the rounds at the moment where someone is complaining that they only got 5000 miles out of their Kumho (worn down nearly to the wire in the middle)…… others are saying “wow, I got 20,000 and still going”. I asked the OP what pressure he was running, and he didn’t know (which is frightening in itself ) He said he would have to check the side of the tyre, because that was the pressure the fitter used. I guess that means he was probably running over 40psi, which would explain shorter tyre life

Pete

[Peter Aawen]

No, it wasn’t a case of not paying attention, Reacher. So many of those responding do not take the time to see that the thread to which to which they are replying is about aftermarket car tyres, and comment that they are running at 16 and 28. Unfortunately, they are in fact referring to their Kenda tyres, but don’t reference that in their response. That is where a great deal of the confusion arises.

There’s an interesting FB post doing the rounds at the moment where someone is complaining that they only got 5000 miles out of their Kumho (worn down nearly to the wire in the middle)…… others are saying “wow, I got 20,000 and still going”. I asked the OP what pressure he was running, and he didn’t know (which is frightening in itself ) He said he would have to check the side of the tyre, because that was the pressure the fitter used. I guess that means he was probably running over 40psi, which would explain shorter tyre life

Pete

Mind you, if he was running over 40psi under the load of just ONE Spyder instead of THREE, then 5,000 miles is actually pretty good considering! But the ride!! It musta been something horrid! Sorta like riding on an unsprung railway rolling stock uni-cycle!! The pain... The pain...

I'd guess his Dentist was a very happy dentist, lotsa work from that bloke, what with all the fillings falling out & the sudden clacking of teeth together every time he hit the shadow of a line painted on the road.... But it musta been a handful in the wet too, probably only marginally safer'n more stable than in-line roller-skating on dry ice while juggling a half dozen sticks of lit dynamite!!