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From: Don Enderton on 23 Aug 2007 14:50
Here is the data; does anyone here know how to perform the calculation?

Old tires are P205/65R15 92V with a load rating of 1400 pounds at 44 psi.

New tires are 205/65VR15 94V (no "P" in front) with a load rating of 1477
pounds at 44 psi.

My car (1998 Honda Accord 4 door EX V6) has a GVWR of 4,235 pounds.

The manufacturer recommends 30 psi front and rear tire inflation pressure
with the original (old) tires.

Question: What should be the adjustment (up or down, and by how many psi)
to take into account the 94V of the new tires instead of the 92V of the old
tires, or, stated another way, to take into account the new load rating of
1477 vs. the old load rating of 1400? Should I now expect to inflate my
tires to 31 or 32 or 29 or what instead of 30?

(It could be the actual load rating of the tires should be equal but because
the new tires don't follow the "P-metric" standard there is a different
table used to express load rating?)

The old tires are Michelin MXV4+ and the new ones are Michelin Primacy MXV4.
Despite the similarity in names, these are different in construction. The
Primacys have a much longer tread wear rating and the manufacturer recites
other differences. The Primacy is the closest tire offered by Michelin for
my make, model and year of car; the original tire model is discontinued in
my size.

Thank you.

- Don


From: John S. on 23 Aug 2007 15:10
On Aug 23, 2:50 pm, "Don Enderton" <Ender...(a)nosuchaddress.duh> wrote:
> Here is the data; does anyone here know how to perform the calculation?
>
> Old tires are P205/65R15 92V with a load rating of 1400 pounds at 44 psi.
>
> New tires are 205/65VR15 94V (no "P" in front) with a load rating of 1477
> pounds at 44 psi.

I would not think any adjustment would be needed since those are
maximum weight ratings. But to be sure I would ask Honda and the tire
company.


>
> My car (1998 Honda Accord 4 door EX V6) has a GVWR of 4,235 pounds.
>
> The manufacturer recommends 30 psi front and rear tire inflation pressure
> with the original (old) tires.

At first glance that seems to be the minimum pressure. If your owners
manual allows it I would consider going a few PSI above the minimum to
improve handling and tire milage.
For instance my car has a range from 32 to 38 psi and I run it at 35
psi.


>
> Question: What should be the adjustment (up or down, and by how many psi)
> to take into account the 94V of the new tires instead of the 92V of the old
> tires, or, stated another way, to take into account the new load rating of
> 1477 vs. the old load rating of 1400? Should I now expect to inflate my
> tires to 31 or 32 or 29 or what instead of 30?
>
> (It could be the actual load rating of the tires should be equal but because
> the new tires don't follow the "P-metric" standard there is a different
> table used to express load rating?)
>
> The old tires are Michelin MXV4+ and the new ones are Michelin Primacy MXV4.
> Despite the similarity in names, these are different in construction. The
> Primacys have a much longer tread wear rating and the manufacturer recites
> other differences. The Primacy is the closest tire offered by Michelin for
> my make, model and year of car; the original tire model is discontinued in
> my size.
>
> Thank you.
>
> - Don


From: N8N on 23 Aug 2007 15:21
On Aug 23, 2:50 pm, "Don Enderton" <Ender...(a)nosuchaddress.duh> wrote:
> Here is the data; does anyone here know how to perform the calculation?
>
> Old tires are P205/65R15 92V with a load rating of 1400 pounds at 44 psi.
>
> New tires are 205/65VR15 94V (no "P" in front) with a load rating of 1477
> pounds at 44 psi.
>
> My car (1998 Honda Accord 4 door EX V6) has a GVWR of 4,235 pounds.
>
> The manufacturer recommends 30 psi front and rear tire inflation pressure
> with the original (old) tires.
>
> Question: What should be the adjustment (up or down, and by how many psi)
> to take into account the 94V of the new tires instead of the 92V of the old
> tires, or, stated another way, to take into account the new load rating of
> 1477 vs. the old load rating of 1400? Should I now expect to inflate my
> tires to 31 or 32 or 29 or what instead of 30?
>
> (It could be the actual load rating of the tires should be equal but because
> the new tires don't follow the "P-metric" standard there is a different
> table used to express load rating?)
>
> The old tires are Michelin MXV4+ and the new ones are Michelin Primacy MXV4.
> Despite the similarity in names, these are different in construction. The
> Primacys have a much longer tread wear rating and the manufacturer recites
> other differences. The Primacy is the closest tire offered by Michelin for
> my make, model and year of car; the original tire model is discontinued in
> my size.
>
> Thank you.
>
> - Don

I would think that the load ratings being so similar and the max
pressure being the same that I would start with the factory
recommended pressure as a baseline and you will probably find that it
is OK. if you really want to nail it absolutely right you could try
chalking your tires.

nate

From: Dan Beaton on 23 Aug 2007 16:08
"Don Enderton" (Enderton(a)nosuchaddress.duh) writes:
> Old tires are P205/65R15 92V with a load rating of 1400 pounds at 44 psi.
>
> New tires are 205/65VR15 94V (no "P" in front) with a load rating of 1477
> pounds at 44 psi.
>
> My car (1998 Honda Accord 4 door EX V6) has a GVWR of 4,235 pounds.
>
> The manufacturer recommends 30 psi front and rear tire inflation pressure
> with the original (old) tires.
>
> Question: What should be the adjustment (up or down, and by how many psi)
> to take into account the 94V of the new tires instead of the 92V of the old
> tires, or, stated another way, to take into account the new load rating of
> 1477 vs. the old load rating of 1400? Should I now expect to inflate my
> tires to 31 or 32 or 29 or what instead of 30?
>

The recommended inflation pressure does not change.

You have load ratings for the tire and the car. If (big IF) you inflated the
original tire to 44 psi, each tire could carry 1400 lb. But the GVWR of the
car is only 4235 lb, or 1059 lb/tire. At 30 psi, the load rating of the tire
would be greater than 1059 and less than 1400. (In fact, you may have a
recommended inflation pressure for maximum load. This would be higher than
the normal inflation pressure.) Inflating the tires to maximum ratings
would result in potentially dangerous handling, as very little rubber would
be touching the road.

The fact that the new tire has a slightly greater load rating has no bearing
on inflation pressure. It does mean that it is a good fit to your needs.

Inflation pressures are determined by the factory to balance handling, fuel
economy and ride comfort. Years ago, the recommended pressure tended to
emphasize comfort over handling, and was lower. Today, safety has a higher
priority, and recommended pressures are higher.

As others have mentioned, you can experiment with inflation pressure to
determine an optimum for your driving, but for most people, the recommended
pressure is a good compromise. Just remember that pressure must be checked
when the tire is cold.

Dan

(This account is not used for email.)


From: Don Enderton on 27 Aug 2007 17:50
Thanks to all for their considered advice.

I've never tried chalking the tires, and don't really know how. Seems to me
the tire would have to be severely over or under inflated for that to show
results, no?

But I used 2 psi above the factory recommendation on the last set of tires
and the wear on them after 65,000 miles was very even.

So with the new set I'll continue that practice.

Thank you all again.

- Don

"Don Enderton" <Enderton(a)nosuchaddress.duh> wrote in message
news:%Fkzi.455314$p47.76565(a)bgtnsc04-news.ops.worldnet.att.net...
> Here is the data; does anyone here know how to perform the calculation?
>
> Old tires are P205/65R15 92V with a load rating of 1400 pounds at 44 psi.
>
> New tires are 205/65VR15 94V (no "P" in front) with a load rating of 1477
> pounds at 44 psi.
>
> My car (1998 Honda Accord 4 door EX V6) has a GVWR of 4,235 pounds.
>
> The manufacturer recommends 30 psi front and rear tire inflation pressure
> with the original (old) tires.
>
> Question: What should be the adjustment (up or down, and by how many psi)
> to take into account the 94V of the new tires instead of the 92V of the
> old tires, or, stated another way, to take into account the new load
> rating of 1477 vs. the old load rating of 1400? Should I now expect to
> inflate my tires to 31 or 32 or 29 or what instead of 30?
>
> (It could be the actual load rating of the tires should be equal but
> because the new tires don't follow the "P-metric" standard there is a
> different table used to express load rating?)
>
> The old tires are Michelin MXV4+ and the new ones are Michelin Primacy
> MXV4. Despite the similarity in names, these are different in
> construction. The Primacys have a much longer tread wear rating and the
> manufacturer recites other differences. The Primacy is the closest tire
> offered by Michelin for my make, model and year of car; the original tire
> model is discontinued in my size.
>
> Thank you.
>
> - Don
>


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