For those with 20" wheels

[stingray72]

This is somewhat crossposted but I think it will get more views here.

I've decided on wheels for my Jimmy. 20x8 Eagle 211's but I'm not sure what backspacing I need.

I've got a 72 Jimmy with an Early Classic 4/6 drop. I'm sure someone around here as the same setup with the drop and 20" wheels. Just wondering what backspacing you're using. I don't want to rub

Thanks

[67ChevyRedneck]

I'm not sure on the backspacing, but I do know that if you're going to run a rim that large you definately need to upgrade your brakes and install larger rotars or you're gonna have a heck of a time stopping!! It would be a good idea to upgrade the rear to a larger drum or even disks! If you already have, great! Just lettin ya know! To help you with the backspacing you need to figure out where you want the rim to sit within the wheelwells. Use the width of the rim to determine this. I would use a piece of cardboard or something. Then using the face of your rotor or drum, where the wheel bolts up, measure from the face to the backside of the cardboard. viola! It also helps to know the height of the tires your using so they don't scrub the wheelwells too....

[mocwon]

Interesting choice, that's exactly what I bought. The engine is not in the truck which is why it sets up so high. I have 2-1/2" drop spindles but I'm probably going to have to lower it even more for the look I want.

I could only find them with 4-1/2" back spacing on the 8X20 version. $1,700 for the set including Goodyear V rated tires, mounting, balancing, lug nuts and tax.

[Smokin72on20s]

i dont have any pics, but i have 20x8s on my 72 with a 4/6 drop and 5" backspace. They are sucked under a little so i am getting some 1" adapters to push them out a little. I'm running 275/45 tires with room to spare, probably the biggest i would go with tires though.

[Deuce]

Originally Posted by Smokin72on20s

i dont have any pics, but i have 20x8s on my 72 with a 4/6 drop and 5" backspace. They are sucked under a little so i am getting some 1" adapters to push them out a little. I'm running 275/45 tires with room to spare, probably the biggest i would go with tires though.

So 4" backspacing would be ideal??

[lolife99]

I'm running 17x8 and 17x9.5 Eagle 212's. The 8's have a 5inch b.s. and the 9.5's have a 4.5 inch b.s. I think the same backspaces would apply to 20's also. If you are going to squeeze a 20x10 on the back,... it will need a 5 inch b.s. (And it will be TIGHT!) Also,... I have ECE's 4.5/6 drop on my '71 2wd blazer.

[lazygaurd]

Why would you need to run larger brakes in order to compensate for 20" wheels. You are not really changing the overall diameter, you are simply running a smaller side wall tire. The overall height isn't going to be much different than running a 295-50-15. You see 4x4's running 33's or 35's all the time which are way bigger and they use stock brakes! Just my opinion but I can't see any need for changing brakes!

[Smokin72on20s]

deuce- from what i see 4" backspace would be ideal, it just depends on if you like the sucked in look or semi-flush look, i personally dont like the sucked in look.

[71swb4x4]

From what I have heard you want bigger brakes to compensate for the extra weight. You are only eliminating a little bit of rubber compared to the amount of metal that you are adding with the larger wheel. That is why most people recommend the larger brakes.

[68w/sbc406]

a set of TSL boggers weigh more than an aluminum rim

[71swb4x4]

I doubt he is going to put TSL boggers on a Blazer with a 4/6 drop :p

[68w/sbc406]

but guys dont upgrade there brakes on 4x4s when they do that. can you imagine how much fender you would have to sawzal out to fit some boggers on a 4/6 dropped truck

[cali_surfer]

Hey mocwon, what color is that? looks gorgeous!!

[Smokin72on20s]

just get aluminum wheels, stay away from the big heavy 20s. i have 20 inch rotary forged aluminum centerlines and the wheels only wiegh 21lbs a piece.

[brad2]

20x8 with 4.5 bs on front and 245/40/20's. Rear is a 20x10 with 5 bs and a 295/40/20. Five inch bs on the rear still didn't fit well.

[68w/sbc406]

got a side pic???

[brad2]

That may be the only pic I took with that setup. Here it is with a 18x8 4.5 bs and a 245/45/18 on the front.

[mocwon]

4" back spacing was what I was wanting but they were not available at any of the Eagle Alloy warehouses so I settled for 4-1/2". Running 275 x 45 tires. I'm with Smokin72on20s on the spacers.

cali_surfer: Thanks. Its the same color code as on '03 Hummer; '04 Avalanche and '05 Corvette.

[67ChevyRedneck]

71swb4x4 is right, you need the bigger breaks to compensate for the larger rim. Its not the weight of the rim, but the rolling friciton and inertia of it. The larger diameter rim creates more inertia and resists stopping more than a 15." you don't have to upgrade brakes. its just safer if you do. and stock brakes with 32" tires on a 4x4....brave! I've seen this conversion on TRUCKS! and several other magazines....they all said the same thing about running rims larger than 16"

[MrShelley]

This is the first time I've ever heard of getting larger brakes just because you have larger wheels. It seems to me that the added weight of a larger wheel would be offset by the thinner (and therefore lighter) sidewall carcass of a lower profile tire. A larger diameter, wider width wheel and tire combination might weight more, but I seriously doubt that it would be enough to warrant changing brakes to compensate for it.

on another note...
brad2, the 20x10 wheel, 295/40-20 tire combination is what I want to use on the back of my truck. Exactly what about the 5" backspacing wasn't right? Too much? Not enough? I'd like your input so I'll know what to order when I get my wheels.

Edit: Actually, after looking at the specs, I'll probably go with a 295/45/20 in the rear. It has a .4" narrower section width than a 295/40/20 so that should give me a little bit more room. I'd still like input from brad2 though on what backspacing he would recommend for a 20x10.

[slogo]

I've got 18x8-4.5 front 20x10-5.5 rear fits great

[FirstGen]

Brad2 - I'm also interested in your input on the 20x10's BS.
Thanks.

[724wdcopper]

no to hijack, but with my 18" 31" overall, i notice absolutely 0 difference in stopping when i switch to my winter 15" aluminum slots with 31" overall height. the difference in weight is maybe a pound or two. my brakes are stock, but i do want to upgrade, just to look cool

i dont think anyone other than a test facility could measure any difference in stopping by changing only rim size, not overall diameter. but hey, maybe i'm stupid and dont know what i am talking about.

[brad2]

5 inches was just not enough backspacing with the 295/40/20. Slogo is probably correct with the 5.5. Also the Jimmy was bagged so if you are not needing to really tuck the tire it would be fine. I had an adjustable panhard bar but it still shifted to much. Maybe if I had the longer ECE panhard bar it would have been better. Had I been running a narrower tire it would have also been better. There you go......not a very definative answer. It was almost three years ago with that setup or I would probably able be able to give a little better answer.

[bagged74]

I had 20x8 with 4.5bs on the front of my jimmy, and 20x9.5 with 5.5bs 245/40 front 275/35 rear tires. It was a 74, so different bodystyle, but i think the backspacing requirement are about the same