Need help from someone who knows wheels and tires!

Hello I'm upgrading from stock 7.5 inch wide wheels with spacers on a 285 70 17 to a 9 inch wide wheel with offset that will equal the same offset as the 7.5's with spacers. I'm planning on keeping the same size tire. Obviously the new wheels will stick out .75" wider on the inside and out. My question is will this equate to the tire sticking out .75 inches wider too?

 

Take the difference in tire width and half it. That's how much wider you are on each side. Now move that out by your offset but minus your spacers. Thats where your tire will sit. If the offset and spacer zero out, then you are .375 further out. 265 is 10.5" and 285 is 11.25. Your total tire width increases by .75, but that is half inside half outside the rim.

 

So basically, you left the wheel centerline the same so you are just adding tire width on each side of center.

 

How thick is the spacer?

 

I know a couple of wheels and tires. They aren’t that fun to hang out with, one is an asshole and the other one drinks too much.

Sorry, I couldn’t resist.

 

Ok so I will Gain .375 out side poke of the tire. Thanks

 

no it won’t, it will be dependent on the tire you actually have and the rim width spec that Specific tire has. Most 285 70 17s are in the 7.5 to 9” rim width spec so that’s “about” the size you’ll get, but the exact size that your asking for will be VERY specific to the actual tire brand & model. Ie not all 285/70/17 are made equally and will be slightly different in Actual/true size on the exact same wheel.

 

So it should be about the same poke staying with the same felken wildpeak 285/70/17 increasing to a 9" rim?

 

1.25

 

If the total offset is the same. And I understood you correctly that it is still a 285 in a Wildpeak.

 

ETA: The backspace on the calculator is incorrect. It's using rim width and not wheel width, so add 1/2" or 12mm.

 

I misread and thought you were in stock tires. 285 to 285 and same overall offset of different rims should be pretty close to even.

 

Seven Inches.

 

about yes. but with close clearance issues 1/8” can make a huge difference. Ultimately the same 285/70/17 will not give you those exact measurements on a 7.5” rim vs a 9” rim. Something has to give to take up the extra rim width, and depending on the tire makeup (usually the sidewall stiffness) it’ll be the “bulge” which is probably what you’re worried about with tire rub.

 

This calculator does not factor in the change in wheel width or does that not matter?

 

I'm noticing a theme in your responses tonight...

 

As @mutely pointed out, the rim width will make some difference. However, the tool I linked to will give you a good starting point to inform your planning. The most important factor is where your tire's centerline will end up.

 

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