19.5" tires?

[Jim_Carolyn]

I've been reading that some folks have been buying 19.5" tires and I assume they are upgrading from a smaller tire. So I have 2 questions:
1) What is the difference between a 19.5" tire and a 18" tire?
2) If you are upgrading, don't you also have to change the rims?

[Kayteg1]

SoCalDesertRider wrote:
Here is a formula to convert metric size to inches

Metric tire sizing, example-

225/70-19.5, where 225 is the section width in millimeters, 70 is the aspect ratio, expressed as a percentage of the section width, and 19.5 is the wheel diameter, expressed in inches.

To convert width, divide the section width by 25.4, which is the number of millimeters in an inch. Therefore, 225 / 25.4 = ~8.9", rounded to the nearest tenth of an inch.

To convert tire diameter, use-

2 x section width x aspect ratio / 2540 + wheel diameter

2540 is a constant in the equation

Example-

2 x 225 x 70 / 2540 = 12.4, + 19.5 = 31.9" diameter

Tire size converter

Those are generic sizes, what compares pretty loose in real life. For good tire size comparison you have to go to tire manufacturer site and find actuall RPM of specific tire model.

[ICamel]

Bedlam wrote:
I used my 275/70R18 Michelin tires as spares for my 245/70R19.5 Dynatrac's. They were were same height even though they were a different width.

X2..........although my spare is a Toyo. Difference in height is 0.07"

[Kayteg1]

JIMNLIN wrote:
JMO..... but 19.5" tires/wheels and are a commercial service combo made to go the distance at max loads all day and nite long. They will have a shorter sidewall which eliminates carcass roll when properly inflated.
They also can have a G or H load rating 110 psi and comes on our 4500/5500 size trucks. A tall heavy truck camper will benefit from a tire like this. These tires may run twice (or more) as many miles of service than the 18" E tire.

OEM 18"/20" comes up to a load E at 80 psi and do a good job for 2500/3500 pickups with 6k-7k RAWR. They can be a little soft for 4k-6k loads in the bed.

Yeah. I had my F450 on 19.5 wheels grossing over 20,000 lb more than once. Don't try that on 18"
It is like comparing diesel to gasoline engine.
Both do the same job, but on quite different level.

[Vinsil]

Mine will carry 6395 lbs per tire.

[JIMNLIN]

JMO..... but 19.5" tires/wheels and are a commercial service combo made to go the distance at max loads all day and nite long. They will have a shorter sidewall which eliminates carcass roll when properly inflated.
They also can have a G or H load rating 110 psi and comes on our 4500/5500 size trucks. A tall heavy truck camper will benefit from a tire like this. These tires may run twice (or more) as many miles of service than the 18" E tire.

OEM 18"/20" comes up to a load E at 80 psi and do a good job for 2500/3500 pickups with 6k-7k RAWR. They can be a little soft for 4k-6k loads in the bed.

[SoCalDesertRid1]

Here is a formula to convert metric size to inches

Metric tire sizing, example-

225/70-19.5, where 225 is the section width in millimeters, 70 is the aspect ratio, expressed as a percentage of the section width, and 19.5 is the wheel diameter, expressed in inches.

To convert width, divide the section width by 25.4, which is the number of millimeters in an inch. Therefore, 225 / 25.4 = ~8.9", rounded to the nearest tenth of an inch.

To convert tire diameter, use-

2 x section width x aspect ratio / 2540 + wheel diameter

2540 is a constant in the equation

Example-

2 x 225 x 70 / 2540 = 12.4, + 19.5 = 31.9" diameter

[Bedlam]

I used my 275/70R18 Michelin tires as spares for my 245/70R19.5 Dynatrac's. They were were same height even though they were a different width.

[Mandalay_Parr]

Yes, wheels must be changed also.

[jimh406]

19.5s have higher carrying capacity all of the way up to 5000 per tire but is dependent on tire. They may or may not be larger overall diameter.

You can search here including archives to get a lot of detail on why upgrade. The best compiled information I've found is actually at the Rickson Tire site. http://www.ricksontruckwheels.com/tires-24570R195.php for example.