tire size question sierra c25

[akinsey]

1980 3/4Ton Sierra C25. Came to me with a hand-made wooden flatbed and standard front-tire size and some HUGE 33.5x12.5 tires on the back.

The problem is whenever I put anything over 200# on the bed (hay, grain, lumber), the bed floor rubs (a lot, i.e. smoke!) on the rear tires.

I thought to replace the 16.5" wheels with something I could get reasonably priced tires on, like 16" wheels, so I found some wheels/tires on eBay in great shape. However, due to my poor measuring ability, the new wheels/tires are the same size (or approximately as tall--265/75/16) as the 33.5x12.5's, thereby not helping me a bit. :/

Question: Is there a smaller/shorter tire/wheel combo I could put on my truck that would allow me to carry any sort of load on it? Or am I stuck with this?
I can provide pictures if it will help.  

Edited by: akinsey at: 12/17/05 11:04 am

[DnStClr]

Do you think the rear springs need a helper, or re-arched?

[roundedline]

Sounds like when they created the bed they didn't take into consideration the droop of the suspension when it is loaded and mounted it too low.  You could try a 30x9.5x16.5 tire which is about 3" shorter than what was on there originally.  

Chris Lucas
www.73-87chevytrucks.com
www.captkaoscustoms.com
Project Su
Jimmy 2WD Project

[akinsey]

Thanks for your responses. I just don't know whether to focus on the suspension issue or the tires, I just want cheapest usability for this truck. I figured tires would be cheaper since there's a mixed set on it already.

Where would I take this thing to get an opinion/estimate for a helper spring/re-arching? Wouldn't additional stiffness to the springs increase the stiffness in the ride? It already rides like a skateboard.

roundedline, If I did my calculations right, according to your post in another thread on tire sizes, a 265/75/16 tire/wheel combo like I recently bought yields a tire height of 31.64, which IS shorter than the 33.5's, but not significantly (or would that 2" be short enough?).

The 30x9.5 you recommended, that's on the original 16.5 rim? I would prefer to go to a smaller wheel size because the tires are more affordable. Any recommendations for a 16" wheel?

Edited by: akinsey at: 12/21/05 1:26 pm

[roundedline]

I can't speak on re-arching springs, I haven't had any success with that.

The 30x9.50 was on a 15" rim since you said you wanted to change, but a 30x9.50x15" and a 30x9.50x16 are going to be the same height regardless of rim diameter, the 30 is the diameter of the rim.

A 30x9.50 should fit under a stock 3/4T truck with no problems, that is why I said they might not have taken into account the suspension and mounted the bed too low to the frame.

Chris Lucas
www.73-87chevytrucks.com
www.captkaoscustoms.com
Project Su
Jimmy 2WD Project

[123 pugsy]

Have you thought about raising the flat bed?

[Lt.Del]

You have a couple of options.

1. throw on a pair of air shocks.  Some don't like em, but if it keeps your ride higher (and i t will) why  not spend the $70.00?  Your ride may suffer a little....gotta weigh the pros and cons.

2.  If you have a welder, grind the rivets of the the front leaf brackets off(where they attach to the frame) and lower them a few inches.  Reweld them back in place...spot weld first to see height.  You may have to get new metal and build up frame a little for the bracket placement.  This really isn't that hard if you have the equipment.

3.  Put blocks on the axle and longer u bolts to bolt the axle to the leafs.

Once consideration of changing wheels/tires is your speedo calibration.


just my 2% of a dollar

SgtDel