Tire Fender Overhang Formula

In a previous thread I created, https://www.tundras.com/threads/max...-stick-out-past-the-fender.10652/#post-185499, I was trying to determine exactly how combinations of wheels and tires result in fender overhang (i.e how much the tire is tucked under the fender) for my '17 CM. I received many great responses and figured I'd create a formula to show the exact(ish) results.

I started by figuring out the distance from the front wheel hub to the fender, turns out it's 90mm (FYI the rear is 105). Using this, I came up with the following formula to determine fender overhang.

Overhang = TW/2 - WO - 90

TW = Tire Width
WO = Wheel Offset

So, for example, on the stock '17 CM with 255/70-18 tires and 18x8 wheels with 60mm offset, the calculation is 255/2 - 60 - 90 = -22.5mm. The same calculation on the rear is -37.5mm, or a 37.5 overhang of fender over tire.

A negative number means the tire is tucked inside the fender, a positive number means the tire sticks out beyond the fender.

What role does the wheel width play?
None. The tire width is really what we're concerned with, the center of the tire is the same as the center of the wheel.

What if I have spacers?
Easy, spacers push the wheel and tire out towards the fender, so therefore add the size of the spacer to the final calculation. Remember 1" = 25.44 mm. For instance, if I added 1.25" spacers (which is 31.8mm) to my stock setup as before, the overhang would be 255/2 - 60 - 90 + 31.8 = 9.3mm, which means it actually would stick out past the fender about 0.37".

Please let me know if you see any issues with this.

 

Nice formula. I haven't seen this before. Yep seems to work, crunched the #s with my set up 295 70 18, +60 offset and 1.25" spacers. Appears to be pretty close.

 

Finally got around to using my formula and finding the wheels and tires I wanted.

Went with the Method Mesh 18x9 wrapped with Yokohama Geolander 295/70-18.

 

Missed this when originally posted, but nice work.

 

Liking the front bumper. I guess that's the one drawback, ya gotta buy a light bar too.

 

Exactly, looks weird without the light bar.

 

I've still got bumper envy though!

 

Thanks for the formula!

BTW on the bumper:

EasyNew 42" 240W Curved LED Work Light Bar IP68 Waterproof Flood Spot Combo Beam for Offroad SUV UTE ATV Truck with FREE 2PCS 18W LED work lights and Wiring Harness and Mounts

https://www.amazon.com/gp/product/B01AA445VA/ref=oh_aui_detailpage_o04_s01?ie=UTF8&psc=1

Fits perfectly. Installed the same bumper with that light bar over the weekend. Going to take some pics of everything installed this weekend.

 

That's a great buy on the lights

 

Excellent work!

 

Mine should in your appendix of grossly improper calculation

 

So using this leads me to believe that a 12.50 wide tire with a +1 offset will set the tire 2.66 inches PAST the fender... Would this be the case? I don't math well and just trying to see if I'm on the right track...

Formula I used... 317.5(12.50) / 2 - 1 -90

Any help is appreciated as like I said before... I don't math well.

 

@joonbug

 

Yes, that's correct.

 

Thanks!

 

Just because... are we talking about the top of the fender or the bottom? Sorry.

 

I would think the top of the wheel well.

 

That's what I assumed as well... but all the pictures that I see with a +1 offset and a 12.5 wide tire do not look like they are out over two and a half inches.

 

So i'm thinking putting my stock 255/70-18 tires on some new method wheels that have a 0mm offset instead of a 60mm offset of the stock steel wheels.

Seems that would make them stick out 37.5mm or 1.5in

Would that cause rubbing in the front?

 

I've seen this thread pop up in recommendations for tire offset a few times now, so figured I'd give it the bump it deserves.

 

You're right. Well deserved bump.
This was extremely helpful. I usually just add "tundras" to whatever I'm google searching and find what thread I'm looking for, but never saw this one. Thanks!

 

I have stock wheels on my SR5 2016, I want my tires to stick out 2” past fenders will a-24mm offset give me that??

 

Here’s some info...
https://www.tundras.com/threads/25mm-vs-25mm-offset.6752/

 

I know old post, unsure if anyone could check my math.

wheel is 18x9 with +20mm offset. Tires are stock 275/65R18.

Calculation= 275/2=137.5, 137.50-60=77.5, 77.5-90=-12.5

so my tire would be in fender well still?


Other offset calculators show about 2 inch poke.

help?

 

Nope. Swap the 60 in your calculation with 20, which is your wheel offset. Should poke about 27.5 or just over an inch.

 

Ok sweet, here is new calculation.

275/2=137.5.

-20 (instead of 60) = 117.5

117.5-90=27.5

is the 27.5 in mm?

if converted to inches 27.5mm in inches= 1.08 inches of wheel poke?


Is this calculation specific for Tundras and our wheel wells?


If I were to take a ruler and place on my wheel to get a general visual, where would I place it?


Thanks again!

 

Here’s what 32.5mm (1.28 inches) looks like.

 

what offset and tire size you running?

looks good!

 

Are you running a +20mm offset with a similar rim like me? 18x9?

 

Missed this when originally posted, but nice work.