i just took my 56 chevy out on saturday for trip into the city for the rumblers show ..as im on the highway in 4th gear my car was reving at almost 3000 rpm's and the car was at about 55 60 mph my tire in the back is a 10xL60x15 old school cheatahs there called i was wondering if i put a taller tire on the rear would it make a diffrance in the rpm's and the speed on the highway i feel like with the 4 speed i cant keep up with the traffic at 70 75 mph...what size rear tire do you recomend ...mind you its a 10 wide slotted rear wheel ..
A taller tire will make a little difference, but it sounds like your diff set needs swapping out for something a bit more cruise friendly. You've probably got a 4.something in there. A set in the low 3s will make a lot of difference.
Help us out , how tall is that tire you run now, and what gear in the back. I know your hoping to get away with just a tire change, and not a ring and pinion.
the tires only say L 60 on them so im guessing there a 60 profile wich is kinda low to begin with ..but there 10" wide and 15 inch ..as far as gearing its gotta be 456 im thinking cause this sum o ***** hums like a mo fo ...
Non posi; jack one wheel up. Mark the tire and driveshaft. Go exactly 2 turns on the tire while counting the mark on the driveshaft. A 411 would be a bit more than 4 turns. 456 a little more than 4-1/2 turns. 488 almost 5 turns. Posi, jack both wheels up and turn the wheel only one turn. Tire swap won't do squat if you are at 4k rpm, do a gear swap
L60-15 is just under 28" tall. Not many p***enger car tires taller, unless you go to a "Pro-street" special tire. Truck tires are taller, but are a lot heavier as well. If you want to do it right the first time, go through the trouble of re-gearing.
thats what im trying to avoid... i feel like i need another gear in the transmission like 5 instead of 4 ....
Relic Stew<SCRIPT type=text/javascript> vbmenu_register("postmenu_5575178", true); </SCRIPT> Member whats taller than this size im running
Tire size will barely make any difference,the only real fix is to change the gear in the rearend,sounds like you are running a 411 now.,might even be 456,thats some high rpms for the speed.
<TABLE id=post5575181 cl***=tborder border=0 cellSpacing=0 cellPadding=6 width="100%" align=center><TBODY><TR><TD style="BORDER-BOTTOM: #e5e5e5 1px solid; BORDER-LEFT: #e5e5e5 1px solid; BORDER-RIGHT-WIDTH: 0px; BORDER-TOP: #e5e5e5 1px solid; FONT-WEIGHT: normal" cl***=thead><!-- status icon and date --> Today, 04:24 PM <!-- / status icon and date --></TD><TD style="BORDER-BOTTOM: #e5e5e5 1px solid; BORDER-TOP: #e5e5e5 1px solid; BORDER-LEFT-WIDTH: 0px; FONT-WEIGHT: normal; BORDER-RIGHT: #e5e5e5 1px solid" cl***=thead align=right> #8 </TD></TR><TR vAlign=top><TD style="BORDER-LEFT: #e5e5e5 1px solid; BORDER-TOP-WIDTH: 0px; BORDER-BOTTOM-WIDTH: 0px; BORDER-RIGHT: #e5e5e5 1px solid" cl***=alt2 width=175>bulldogmafia<SCRIPT type=text/javascript> vbmenu_register("postmenu_5575181", true); </SCRIPT> Grenade Inspector </TD></TR></TBODY></TABLE> i dont think itd bigger cause i spoke to someone at richmond and they said the biggest you can fit in a stock chevy rear was a 411 withouit changeing out the carrier ??
F&J a question, I was taught for a open rear or non posi, you have to hold one wheel from turniing to get a accurate reading as you described. Just asking please dont take offense.
brad chevy<SCRIPT type=text/javascript> vbmenu_register("postmenu_5575194", true); </SCRIPT> ya telling me i was like wtf i wanna go faster on the highway ..lol. im not worried about gas milage..even with a tunnel ram it only used 15 bucks worth of gas on a 80 mile trip
Yes, and that's why I said "jack one wheel up" Also to get a super accurate reading, put a chalk mark on the driveway or floor to line up with the tire mark. The driveshaft, make the mark at the rear yoke with another mark on the pinion snout. And take the slop out of the rear in the direction you will turn the tire, before making the marks.
wow, I just ran the numbers and you have to be at about 4.80 or deeper if your rpm figure is accurate. I bet just switching out to something in range of about 3.50 to 3.73 would make a huge difference. Ya, just running the numbers real quick and figuring your rear tires at 27.5" I get 2734 RPM at 60mph with 3.73 gears.
From your post you said that on the highway at 55-60 mph your engine is turning 4000 rpms and you wanted to know if tire size would help,no it won"t ,the only way you are going to be able to run at 70to 80 down the highway and keep the rpms down is to change the rear gear,and in the process take alot of stress off the engine,what don"t you understand about that.,and at the same time you will get better fuel mileage whether you give a**** or not.
Yes, of course, a larger diameter tire will help; <TABLE id=table17 border=0 cellSpacing=0 cellPadding=5 width=400><TBODY><TR><TD vAlign=center rowSpan=2 align=right>Mph = </TD><TD vAlign=center align=middle>rpm x tire diameter</TD></TR><TR><TD vAlign=center align=middle>Gear ratio x 336</TD></TR></TBODY></TABLE> <TABLE id=table16 border=0 cellSpacing=0 cellPadding=5 width=400><TBODY><TR><TD vAlign=center rowSpan=2 align=right>Gear ratio = </TD><TD vAlign=center align=middle>rpm x tire diameter </TD></TR><TR><TD vAlign=center align=middle>Mph x 336</TD></TR></TBODY></TABLE> <TABLE id=table18 border=0 cellSpacing=0 cellPadding=5 width=400><TBODY><TR><TD vAlign=center rowSpan=2 align=right>Rpm = </TD><TD vAlign=center align=middle>mph x gear ratio x 336</TD></TR><TR><TD vAlign=center align=middle>Tire diameter</TD></TR></TBODY></TABLE> <TABLE id=table27 border=0 cellSpacing=0 cellPadding=5 width=400><TBODY><TR><TD vAlign=center rowSpan=2 align=right>Tire diameter = </TD><TD vAlign=center align=middle>mph x gear ratio x 336 </TD></TR><TR><TD vAlign=center align=middle>Rpm </TD></TR></TBODY></TABLE>
lorodz, It not much fun running on the highway with the wrong gears. I've been experiencing the same problem with my 46 ford. The good news your tires might be older than dirt. It's been awhile since I've seen new tires with letters for width instead of the size and aspect ratio. **** I could be wrong, and you could find a nice set of 34" tall tires that work for you. Check out this link for a calculator for gearing and tires Good luck- http://vexer.com/automotive-tools/speed-rpm-calculator
And I was wrong/ AGAIN!!! It's a 275/60 15 Some folks on the net sell them. But I'm still doubting getting those tall tires under it. Good Luck
brad chevy<SCRIPT type=text/javascript> vbmenu_register("postmenu_5575233", true); </SCRIPT> Alliance Member what don"t you understand about that 1st off never said anything to make you get all huffy..never said i didnt understand that! or anything else for that matter.. as far as what i do understand i understand that a taller tire and a smaller gear will reduce rpm's ..what im asking is how much will it reduce rpm's ? i really rather not change the rear if it is a 411 or 456 ...so maybe add a t-5 for the extra gear and add a bigger tire . instead of trying to find a rear that will work..i already have a t-5 and im shure 2 tires are cheaper than a 12 bolt rear with gears .its just a ?
If you are at 3000 rpms at 60 and the tire is 28" tall (275/60) you have a 4.10 gear. This is a pretty tall street tire. Seems a gear change to a 3.55 would be the easy answer to your problem if this is mostly a street driven car. That would get you down to around 2600. My web site has a link to a spread sheet for finding mph/rpm/gear ratio. Just plug in your numbers and it does the rest. www.hrracecar.com It is under the heading Technical Stuff. It would take a 33" tall tire to get you down to around 2500 rpms at 60. Hope this helps.................Toni
A calculator will set you free... <TABLE id=table17 border=0 cellSpacing=0 cellPadding=5 width=400><TBODY><TR><TD vAlign=center rowSpan=2 align=right>Mph = </TD><TD vAlign=center align=middle>rpm x tire diameter</TD></TR><TR><TD vAlign=center align=middle>Gear ratio x 336</TD></TR></TBODY></TABLE> <TABLE id=table16 border=0 cellSpacing=0 cellPadding=5 width=400><TBODY><TR><TD vAlign=center rowSpan=2 align=right>Gear ratio = </TD><TD vAlign=center align=middle>rpm x tire diameter </TD></TR><TR><TD vAlign=center align=middle>Mph x 336</TD></TR></TBODY></TABLE> <TABLE id=table18 border=0 cellSpacing=0 cellPadding=5 width=400><TBODY><TR><TD vAlign=center rowSpan=2 align=right>Rpm = </TD><TD vAlign=center align=middle>mph x gear ratio x 336</TD></TR><TR><TD vAlign=center align=middle>Tire diameter</TD></TR></TBODY></TABLE> <TABLE id=table27 border=0 cellSpacing=0 cellPadding=5 width=400><TBODY><TR><TD vAlign=center rowSpan=2 align=right>Tire diameter = </TD><TD vAlign=center align=middle>mph x gear ratio x 336 </TD></TR><TR><TD vAlign=center align=middle>Rpm </TD></TR></TBODY></TABLE>
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