19.5 Wheel and Tire???.

Edited ... No experience with GM suspension.

First thing is to find out what your rear axle load is.

I was reluctant to go the 19.5 route for various reasons. We purchased GM OE steelies from a 1 ton and went with 285 Nittos for 7500# rear axle capacity, which was more than enough for our Eagle Cap and still keep an OE tire/wheel combo.

My thoughts are if you NEED 19.5's...you should probably go get a dually.

Good luck, Bill
(flame suit on)

I did not find that there waa a significant weight difference between my 285/75r16 and my 19.5 245/70R19.5s. that said. steel rickson wheels, lead time 7 to nine months. vision aluminum 19.5 wheels two to three days.

The steel 19.5 wheels are heavier than 19.5 Aluminum wheels. I went with Visions Aluminum mainly because of cost and no wait time. For years I used the stock 17" forged aluminum wheels and Nitto 285 Terra rated at 3750 lbs. and later 285 Nitto Durras rated at 3970 lbs. Great tire but did change my speedo about 2.5 mph. I went to 19.5 vision wheels and tires and noticed a big difference in better handling and less sway! Also my speedometer did not change. Still the same as Nittos..2.5 mph difference according to the GPS. The Nitto tires although has better load index than stock tires but the soft sidewalls are no comparison to the stiff side wall of the 19.5 tires. 19.5s are the way to go IMHO if you want to stay with a SRW truck and heavy hard side TC... Period...

Four tires mounted on rims and palletized weighed 550 lbs when delivered to my home. I had 245/70R19.5 tires on aluminum rims. Your GM will only fit the 225/70R19.5 unless you modify suspension or wheel well liners, so they will be slightly lighter.

The Rickson rims are heavier steel with a 5000 lb load rating using OEM offsets. The Vision rims are lighter aluminum with a 4500 lb rating using greater outside offset which gives the truck a slightly wider stance. Some people will argue that the larger offset will affect wheel bearing and tie rod life, but no one has come back with proof. I chose the lighter aluminum rims knowing I was not going to exceed 9000 lbs on either axle but chose 16PR rated tires to get the stiffest sidewalls.

The Rickson web site lists the weight difference between 19.5 steel vs aluminum wheels, 45lbs for Vision and 57 lbs for Rickson steel. I like my Rickson wheels/tire combo but you better be willing to wait. It "only" took 4 months for me to get mine.

My 4 wheels with correct OEM offset and 245/70R-19.5 Firestone Fd690 plus tires (load capacity 4545lbs) which are more than sufficient for any gravel / forest service road cost under $3400.

I noticed a modest improvement in handling in going from 3195@80 PSI tires to Nitto rated at 3750@80PSI. The 7500 lbs. for the rear pair provided for a payload of 4200 lbs. with my truck and that was more than enough.

I chose not to spend the $4000 on a set of 19.5 rims and tires as they were not needed, the ride without a load would have been much harsher, and the treads are limited to highway use types that would not be very good for use off the pavement. The added weight will result in more wear on the front end suspension and important to stick with the factory offset with whatever rims you choose.

With a 3700 lb. camper load the biggest improvement in handling came from adding an extra rear leaf to each side of the truck. Most of the motion was from the overloaded leaf springs and the greater range of travel made it difficult for the Rancho shocks to do their job as well. Part of the problem was that in a turn the downhill leaf springs were having to handle more than 50% of the load in the bed. Increasing the leaf springs load capacity from 4,000 lbs. to 5,000 lbs. made a big difference in handling.

To address some of WinterSun's post:

1. Many OEM rims are not rated for much over 3500 lbs, so research this before spending money on higher rated tires.
2. A set of four 19.5" tires and rims can be purchased for as low as $2000.
3. The whole idea of going with 19.5" tires to handle weight better. You cannot do this with a soft sidewall tire. If you are looking for a soft unloaded ride or flotation in sand, these are not the tires for you. They will improve load ride and handling.
4. There are aggressive traction treads as well as street treads for 19.5" tires. As with any tire, the more aggressive ones wear faster and make more tread noise than the street tread. I had no issues on forest/logging roads or snow with 19.5's.
5. Although additional tire weight and rim offset has been thrown around numerous times, no one has provided links to substantiate aggressive wear or premature failure due to the use of 19.5's.
6. Suspension spring rate is only part of carrying a load. Proper tires for the job is another part. Then we have shocks, stabilizer bars,...

I swapped my 16's on my f-350 srw for the Vision wheels with Sumitomo 245/19.5's.st918 tires I choose an aggressive tire because of wanting better traction. I am very happy with the wheels and tires around 8,000 miles so far, there is a hum from the tires but well worth the noise for the extra safety of 4500 lbs per wheel factor. Cost was $2,197.00 priceless for the peace of mind.

On my dually the stock size was 235/85-16 on aluminum Alcoa's which weighed 73#. The Vision aluminum wheels with 225/70-19.5 tires weigh in at 114# each. The measurements were done with a bathroom scale so plus/minus a couple pounds, but that gives you an idea.
Btw, I love 'em and will never go back to a 16" E rated tire.