can someone tell me if my math is correct here. im looking into a 9.5 in wheel with a +15 offset.

right now i have an 8.5 in wheel with a +35 offset.

8.5 in = 215.95mm or 107.95 on either side of the center.

i figure if you subtract the +35mm offset from the 107.95mm side you get 72.95mm. therefore the wheel sticks out 72.95mm front the point were it bolts to the hub.

now if you do the same for the 9.5 in wheel...

9.5 in = 241.3mm or 120.65 oin either side of the center.

Subtract the 15 offset from the 120.65mm side you get 105.65mm. so the 9.5 +15 sticks out 105.65mm from the point where it bolts to the hub.

now if you subtract the 72.95mm from the 105.65mm you would get the difference in stick out from the 9.5 +15. This makes a difference of 32.7mm.

therefore i can expect the 9.5 +15 to stick out 32.7mm(1.28 inches) further than the 8.5 +35 that i have right now.

Is this correct. sorry this may seem a little crazy. im just trying to understand offsets and wheels and all that.

 

bump i'm curious.

shouldn't you take into account the width of the tire you are running as well? i presume your worried about having to roll your fenders?

 

yes i am worried about the fender rolling. Im also trying to get an idea of how it would look, if my math is correct, 32mm seems like quite a bit. ive seen pictures of cars with +15, but nothing in person.

i did not take into account tire width, but i would imagine it would be a matter of +1 or 2 mm assuming that the tire sits even with the rim. im not looking to go very wide on the tires. i may even stretch my 245's until they are done, theyve got 90% tread left, when they go i will up to 255's.

 

Either way, you're prolly going to have to go widebody out back. The Evasive Evo runs 18x9.5 +12 TE37's. It has the Voltex rear fenders, and Chargespeed front fenders just to get them to clear.

 

its been done with some rolling and pulling of the fenders, im just trying to get an idea of how it will look

 

It'll kick out about 1.3 inches past the fenders, even with camber it's gonna stick out quite a bit, and prolly wont look all that great unless you have body lines to compensate for the wide track. That's just my opinion.

I'm running 17x9 +22 offset with 255's (actually measures up closer to a 265) with cut fenders out back and they come out about a millimeter past the fender with about 1.2 degrees of camber. It looks really flush and even kicks out very very slightly which makes it look meaner, but i've decided to go with something else.

 

looks good in pictures...

 

While your math is correct, I have to ask if you've taken into account the fact that more of the rim will be sticking in due to the less positive offset, potentially rubbing against the strut and the fender splash liner/gaurd when the wheels are turned full lock.

Not to mention this is also going to mess with your scrub radius. It will also put added stress on your wheel bearings.

 

The wheel is 1" wider, and the outside of the wheel is 1.28" further out from the hub. He's actually gaining space on the inside, not losing it.

Higher offset = wheel moves inboard, lower offset = wheel moves outboard.

This kind of stuff makes me wonder why so many manufacturers use offset instead of backspace.

 

all of this math is kind of confusing for me i just use this web site to figure out what i want.... i want to go with a 18x10 rim

http://www.1010tires.com/WheelOffsetCalculator.asp

 

True, dunno what I was thinking ... The rim would stick "out" more ....