What size tire do I need?

[Trip59]

The tires in the pic below are 205 70 15 the wheels are (of course) 15" but I'm not 100% on the width, either 6 or 6.5. I have a set of 7" rims, but the backspacing doesn't fit on the front.

So, the plan (and here it gets tricky) I have three ok tires and three ok rims. the one bad tire is on one of the good rims, and the one bad rim has one of the good tires on it. Those two are coming off the truck and will be swapped and saved as a spare. The rims look nearly identical in appearance to the others I had (what a coincidence), so I'm going to take the two good tire/good rim pair and put them on the front, and the two bare rims, with new tires, in the rear.

I just lowered (half done) the truck but can't do an alignment yet, so I'm not looking to put new tires up front, and hopefully within the year I'll be replacing the wheels all the way around, I've picked what I want, but at $90 a piece, plus new tires, it's not a 'right now' purchase when I can get by for another year with by just buying two tires. And yes, I will be getting it aligned within a couple hundred miles after the drop, I just have to fix or replace the gearbox first so I don't have to argue with the techs (I used to be one, so I nkow it can be done, but they'll half-ass it and say it's the best they can do).

So, 7" wide 15" rim, same height or a bit taller, what size?

[Inked Okie]

Ok Trip I have read your message 3 or 4 times trying to get this straight.

Are you going to run the 205's on the back and asking if you should go a with a bit taller on the front wheels? I would'nt.

If that is your question... and you are wanting to only buy 2 new tires, buy 2 new 225's or 235's mount them on your rear wheels and mount the 2 best 205's on the front wheels.

I would prefer at least a 255-275 for a truck tire, but if you went that tall on the rear with 205's on the front it would look weird.... Just my opinion.

I hope I understood correctly....sorry if I did'nt.

[Trip59]

Sorry, I wrote it three or four times...

Basically, I have two good tires and wheels on the truck now, I'm moving them to the front, they have 6-6.5" wide 15" rims with 205-70-15 on them.

I have a full set, but will only be using two, 7" wide 15" rims for the rear. I'm trying to figure out what size tire to put on the rim that's an inch wider, to make it the same height, or possibly a bit taller. Would a 235-75-15 go, or should I do 255-75. I did tires for a living 20 years and a lot of beers ago, so I know that a 75 is taller than a 70, BUT it's also relative to the width, so a 255-70 is going to be taller than a 205-70.

Trip

[Inked Okie]

Ok got it....... the 205-70-15s are 26.3 inches diameter
A 235-60-15 would be 26.1 inches in diameter
A 245-60-15 would be 26.6 inches diameter
A 255-60-15 would be 27.0 inches

Hope this helped.

[Trip59]

Wow, ok, so I was way off in what I was thinking. Now, how does the inch wider rim factor in...?



Trip

[Inked Okie]

A 60 series tire would be the widest I would go on a 7" wheel... I will be fine.

[Trip59]

um, I missed something, the 60 is the height profile in ratio to the tread width... that would be chosen to set the height based on the width chosen, 205, 235, 255, etc. That's what I was wondering, which of those would work best on a 7" without it tapering or looking like a pumpkin.

Trip

[NC67Chev]

I've found this site helpful in determining the tire height when changing widths/ratios:

http://www.jekylhyderacing.com/HeightofTires.htm

I hope this helps.

[Pickupmanx2]

This is handy, I am going to go with the 265/70/15's on my 70, probly use the factory rims for now,,,, might be a little odd looking, but it has got to be better than the P225's that are on it now. They are car tires with a 1760lb @ 35psi squishy as all hell..

http://www.herculestire.com/catalogH...acAT-part1.pdf