19.5 tire question

Without naming each poster the following is a response to most of the posts in order: As I stated in a earlier reply there are trade offs to every gain in performance in regards to tires and wheels. ie; 19.5s are heavier and thereby have their own set of issues. More stress on unsprung parts.

Performance perramaters improve as the tire ages...tire life and mpg.

The tire when new provides a better ride.

It's the amount of air that a tire can carry that allows for greater load carrying capacities.

When higher air pressures are needed they can be obtained easily at any tire dealer at no charge.

As to deep lugged tread designs...those with the more aggressive deeper treads are torque eaters, which simply means less mpg and overall performance when under load. This is greatest during the first 10 to 15% of tires life. And so the greater use the more cost and less performance.

Sidewall flex...all 19.5s, 22.5s and 24.5s are constructed the same...stiff.

This wasn't mentioned but a common dis-belief is that some tires are softer or harder than others...not true. All highway use tires, from a VW to a KW use a 72 hardness compound. The only time a tire will seem like it's harder is when it dries out and looses its' elasticity. However it still retains its' 72 hardness.

The best wheel tire combo is steel wheels and radial tires. However pretty alloy wheels look they do not compliment a radial tire as well as a steel wheel. Steel wheels flex...alloys do not. The preference is to have a combination wheel tire that both flex...not to have a tire doing all of the work. In this case 19.5s don't flex much but some is better than none...

And remember that all of the above is related to a dynamic rather that a static situation.

I have a 05' Chevy and I have Vision's with the 608's also. If you look at the weight capacity of the 225 vrs the 245 it makes no sense to get 225. Its like paying the $3k for what 5-600lbs over what I could get with some Nitto's. I had les schawb do the 245 and they did trim some off the front,it rubs barely at full lock. The wheel/tire combo is unreal!! I just came back from an elk hunting trip and was in some good winds gusts to 40mp,I had cruise set at 66 and all was rock solid! They get things dirty so be ready to wash lol. Adam

I have an 08 duramax and the 608's with the vision wheels, the biggest tire i could fit was the 225 without rubbing. The 225's are a little wiggly at higher speeds but I dont drive it like a race car so it is ok.

As far as TPMS goes, it will work but you need a sensor that goes up to the higher psi's and the check tire light will be on all the time. Supposeldy you can get the computer reporgrammed to work at higher psi's but I have not tried it as I dont want to take any chance of voiding my warranty.

For those with the NNBS GM trucks (mine is 2012). These aren't 19.5" tires/wheels, but big stuff does fit under there with very minor mods.

My local shop fit 285/75-17 Nitto Dura Grapplers by slightly pulling the rear part of the front fender liner back with a couple HD zip ties and one full turn of the T bars.

2004 1/2
It has the LLY Duramax.

GoFish,

What year GMC do you have?

I've been using the Dunlop SP 431 245x70x19.5s on a set of Rickson forged aluminum wheels. They can be a little too stiff for running unloaded, but the much reduced sidewall flex with the camper on is worth it. Compared to 16" tires, the 19.5's don't allow as much sidewall roll on corners and they track really well on the highway. Plus the added weight capacity takes a load of worry off my mind, since I am slightly over 11,000 lbs GVW when leaving for a trip.

I have a set of aftermarket mud flaps and when the tires were new, they would just rub the drivers side mud flap when backing up with the tire at full left lock. Since they have worn in though, the rubbing has stopped.

I would never go back to 16" tires as long as I'm going to haul a camper. These 19.5's work so much better.

Catsmobob wrote:
I have ran Rickson steel wheels with 245-70-19.5s Michelin xds tires for 5000 miles and only had two slight rubs on hard uphill bumpy turns.Thats with no wheel well mods. They are almost identical in size to the 265-75-18s that came on my 2011 Chevy 350 SRW. They are H rated tires that handle great but they do sing.

I think the 2011s have a slightly larger wheel well.

I have ran Rickson steel wheels with 245-70-19.5s Michelin xds tires for 5000 miles and only had two slight rubs on hard uphill bumpy turns.Thats with no wheel well mods. They are almost identical in size to the 265-75-18s that came on my 2011 Chevy 350 SRW. They are H rated tires that handle great but they do sing.

wintersun wrote:
I forgot to mention but I find that most tire pressure stations do not provide the 85 PSI air pressure I want for my current tires so that after they cool down they are close to 80 PSI. Going to a higher G or H load range tire would make that even more difficult to get 110-120 PSI unless I carry around my own compressor.

I learned this a long time ago with my first set of 19.5,s. If you need airing up over 80PSI, just find a tire or vehicle repair shop and they will be able to supply almost always,120PSI.

Dave