# 33-10.50R15 BFG AT/KO

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by 1990SilveradoK5, May 4, 2001.

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Got a set on order today, can not wait until I can be styling with larger shoes.

What effect will this have on my Speedo, etc? If I do the math correctly it should knock off 4-5 MPH on it.

Gone Large and Loving It.
Keith

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3. ### kumma1/2 ton status

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Please post a picture of the truck after you install the tires, i have some rims laying around that i want to put those tires on.

thanks
craig

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5. ### Sparky1/2 ton status

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Careful with the calculater, you have to realize that the faster you go the further off the speedo will read. Its not a linear function. As in, if you were to graph the speed it is off by vs. the actual speed the graph would not be a strait line. It will be off by about 5-7 at 80mph and about .2 at 5mph.

When all else fails... Check the blinker fluid.
78 K-5

6. ### dyeager5351 ton statusPremium Member

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Good point. From teh calculator, you need to figure the % your speedo is off. At 10%, you will be 3.5mph off at 35, but 6 mph off at 60....you wouldn't think it matters, but had a friend just get a ticket for 4 mph over the speed limit. Tire size as well is not a constant, as 33" tires, last I checked at BFG's page (I think it was there) they said the tires were actually 32.9". I'd figure it out with a speedo check station (the freeway mileposts that are set up very accurately, not the standard ones), and a stopwatch.

Dorian
My K5 and Chev/Olds tech/links page: <A target="_blank" HREF=http://www.dorianyeager.com/index2.html>http://www.dorianyeager.com/index2.html</A>

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Where would I find the parts and how too's needed to adjust my speedo?

Since it is my daily driver I want it to be close.

Gone Large and Loving It.
Keith

8. ### mudhogTHEGAMEStaff MemberSuper Moderator

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i would just take it in to a shop and have it re-calibrated then you will get the best acuracy and it dont cost that much less than a speeding ticket lol

77blazer see it at<A target="_blank" HREF=http://community.webshots.com/user/ssmith6333>http://community.webshots.com/user/ssmith6333</A>

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10. ### 2Dogs1/2 ton statusPremium Member

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Or - pick the speed you want to be going and knowing all you ratios and tire sizes use the calc to determine
the RPM for that speed.... Will that work? I think that is how they keep the Nascar drivers at speed on pit lane.
I use the dangerous method of following the fastest guy on the road.....
And my record you ask? 2 tickets in 5 minutes in 2 states (crossing from Ca into Or). So on second thought
ignore all my posts - HA. Dave

11. ### CV2021/2 ton status

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Your's should use a VSS (electronic speed sensor) at the T-case, if it still has the 241C. Check out the Superlift TruSpeed. There's a quick blurb about it on page 8 of June 2001's 4Wheel Drive & Sport Utility Magazine. Looks like it sould work.

Why do people keep calling it a Bronco!!!!!

12. ### dyeager5351 ton statusPremium Member

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Is your speedo electric?? Someone brought that point up, and my dad swears he got an electric speedo out of a later Suburban (still our body style though) I didn't think ours EVER went electric, but who knows...so is it wire or cable? : )

Dorian
My K5 and Chev/Olds tech/links page: <A target="_blank" HREF=http://www.dorianyeager.com/index2.html>http://www.dorianyeager.com/index2.html</A>

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I believe it is electric, but I will look at it tonight and let you all know.

Gone Large and Loving It.
Keith

14. ### dyeager5351 ton statusPremium Member

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Should be easy to tell right at the transfer case. I believe even then it would be gear driven, and as long as there was a wide variety of gears, you should be able to just change them.

Dorian
My K5 and Chev/Olds tech/links page: <A target="_blank" HREF=http://www.dorianyeager.com/index2.html>http://www.dorianyeager.com/index2.html</A>

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OK, I agree that it is easy if you know how to do it. And yes it is an electronic gauge.

dyeager535 could you provide a short step by step that would get me through it? I have done almost all of my own work since owning a garage, however this is my first 4X4 working with transfer cases and such.

Also how do I know what gear to replace the stock one with?

Gone Large and Loving It.
Keith

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Can't hardly wait, received the call this morning and my tires are in. I will be getting them installed tomorrow morning, if I can get ahold of a digital camera I will get before and after picures of my truck and put them up on my site.

Can't wait, Tires tomorrow and shocks this weekend. Should ride like a different truck by Monday.

Gone Large and Loving It.
Keith<P ID="edit"><FONT SIZE=-1>Edited by 1990SilveradoK5 on 05/08/01 09:49 AM (server time).</FONT></P>

17. ### dyeager5351 ton statusPremium Member

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I really can't guarantee that my method will work. I've changed numerous speedo gears, but all on 2WD (no t-case) mid 80's (no electric speedo) GM cars. All you have to do though, if the gears aren't too far off (yours shouldn't be) is find where the speedo wire goes on the t-case. Usually one bolt clamping the speedo sleeve to the t-case, kinda like the distributor hold down. Unbolt that, and twist/pull (don't pry if the piece is plastic, they WILL break) the assembly out. There should be some type of driven gear (drive gear should be on the t-case output shaft, "under" the speedo driven gear. Once you get it out, that gear probably just pulls out or something, and its just a matter of getting one with the right tooth count to compensate...all GM speedo gears I have seen so far have the tooth count stamped on them somewhere (usually small) so there is no reason to count teeth.

Glad you got the tires...lets see some pics!

Dorian
My K5 and Chev/Olds tech/links page: <A target="_blank" HREF=http://www.dorianyeager.com/index2.html>http://www.dorianyeager.com/index2.html</A>

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Just drive the same speed what the people around you are doin....My speedo has been off for about 4 years now.

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Watch for the muzzleflash!
Correction Eric, just drive about 10 MPH slower than every body else and you'll be doing the speed limit LOL!

<font color=blue> I'd rather have a bottle in front of me, than a frontal lobotomy!

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