Change gears or tyres?

[retroboy]

Howdy
Long story short version I ran a basic small block Ford FED 35 years ago with 4.11's 28.5 tyre leaving at 3000 (clutch auto) about 6300 through the lights (1/4 mile) I went to a 30.5 tyre and it was a dog slow thing to drive. Now I have a basic 400ish HP small block Chrysler with 4.3's 31 tyre and a converter leaving with foot brake. I've only run it once 1/8 mile and hurt the motor and had no second gear so have no info. I've been thinking of going back to a 30" tyre  to help it off the line. Today I woke up thinking it would be cheaper to change to a 4.88 or so diff centre and leave the existing tyres and rim. Anyone changed gears rather than wheels and tyres?  This is an 1/8 mile car with a three speed trans (2.45:1 first gear) and 6500 it will be all out of breath. I haven't done the maths on the gears so don't shoot me down over that.
Cheers
Retro

[masracingtd1167]

At 6500 rpm would put you around 123 mph .

[retroboy]

Yep at about a mid 5 which should put me into the fun at these regional tracks. Just need to get a bit of help at the first half of the trackhence the question
.

[digster]

Are you running an 8 3/4 Chrysler gear?

[jeff/21]

 i prefer a low gear and tall  narrow tires we run 4.88 with 33x10.5 it all depends on the track conditions

[retroboy]

Are you running an 8 3/4 Chrysler gear?

No Mate a 9"

i prefer a low gear and tall  narrow tires we run 4.88 with 33x10.5 it all depends on the track conditions

I'm looking to go to a 10" tyre coz the two tracks I would travel to are good was looking at Hoosier 18205 - 30.0/10.5/15. However a pair of wheels and two slicks would set me back some where close to $1500 Aussie Dollars some it might be easier (dollars) to put a killer gear set in with my existing 31/13/15 M/T.

Tell me which is the better way to go and why you think so? Who's gone down either path - would you do it again?

Cheers

[digster]

 Bill hit the nail on the head. A 31" tire and a 4.88 gear would give you the 6500 RPM @123 you're looking for. A 9" is fairly cheep and ez to build for a 400 hp application. My 2 cents would be, run the 31 inch tires. Keep your 4.30 gears in case you get a chance to run 1/4 mile tracks. Build up a 4.88 center.
(dang the bad luck I just sold off a set of 9" Richmond 4.88 pro gears cheep)

[Paul New]

Gears but you definitely could use a narrower tire

[Scott Krieger]

13" is a lot of tire to have to pull for sure. We have a lil 500hp BBC in our car. We run MT3062w, 29.5x10.5x15 tire on a 12" rim w/stiff side walls and use a ford 9" w/3.90 gear.
I hate to spend money on the car, because it has to be accountable. It's my Daughters car and she pays all the costs, so ROI is very important for me.
What about putting it back together with what you have already and getting in a few pass to see what the car wants and likes. Maybe try airing up the tires then as you go, to get tire off the track and see if it makes it happy. Always nice to have a good spair set of tires around that's for sure.

Best of luck

[Scott Krieger]

Race cars are like females, as we know. What we think she wants is not what she wants at all. Give her what ya got, be astute & run it. Give her what seems to make her happy as ya go, weather it makes sense always or not.
I love setting back after the races thru out the week reading the log book and watching video trying to understand what the car (Victoria) is telling me makes her happy. Making adjustments for next race and running it.
My daughter Kayla log's all our data at the track. As all I focus on at the track is the moment. Track, Wind & D.A. and so on.
As we know also that what made her happy last time, my not result the same next time. (to close to the edge!)
It only took us 3 years to finally get ours happy to the point of just draining the carb and put her on the stand for the next race. Lot more accountability on the driver when the car is happy which makes it a lot of fun.

Enjoy your digger 

[George]

I think it has been said a time or two here but you could gain performance with less tire. I would compare tire weight. The more you can reduce the rotating mass the quicker the car will react and perform . I have tried several Goodyear and Hoosier sizes and nothing has been quicker than the GY 2885. I run Hoosiers now because we live 10 minutes from a Hoosier warehouse. Good luck and have fun. George

[JrFuel Hayden]

George, do you mean D2585, Goodyear 31x12x15 that is 22.6 lbs ? What Hoosier are you happy with ?
I still have the D2585 available.

Jon, Hayden Wheels

[George]

George, do you mean D2585, Goodyear 31x12x15 that is 22.6 lbs ? What Hoosier are you happy with ?
I still have the D2585 available.

Jon, Hayden Wheels

Oops, yes Jon its the D2585. Now that we are running a blown combination the weight disadvantage isn't such a big deal. I have run well with the Hoosier 30189652. I am not sure if is a good catalog number . I had bought a set of the 31.0/12.0-15  #18225 and went back to the warehouse and got in contact with a racing rep with a complaint of the tire being heavy and they sent me the set without a charge. As I recall it was 5lb lighter so it was about 25 lbs.  As I understand it Hoosier built the #18225 as a JR fuel tire ? https://www.hoosiertire.com/pdfs/jrfuel3112015.pdf

Please send me a quote on a pair of the D2585 shipped to a commercial address 62703. Thanks George.

[wideopen231]

just for fun I ran tire change thru drag simulator.1" chnage in tire =.005 @60',320 rpm @ 1/8 and 295 rpm @ 1/4 mile.  Now this was with 4.11 gear and more motor than OP. IMO its very little.since gear set is half cost of new slicks or even less if need wheels,I would think gear change would be best bang for buck.

[JrFuel Hayden]

George, do you mean D2585, Goodyear 31x12x15 that is 22.6 lbs ? What Hoosier are you happy with ?
I still have the D2585 available.

Jon, Hayden Wheels

Oops, yes Jon its the D2585. Now that we are running a blown combination the weight disadvantage isn't such a big deal. I have run well with the Hoosier 30189652. I am not sure if is a good catalog number . I had bought a set of the 31.0/12.0-15  #18225 and went back to the warehouse and got in contact with a racing rep with a complaint of the tire being heavy and they sent me the set without a charge. As I recall it was 5lb lighter so it was about 25 lbs.  As I understand it Hoosier built the #18225 as a JR fuel tire ? https://www.hoosiertire.com/pdfs/jrfuel3112015.pdf

Please send me a quote on a pair of the D2585 shipped to a commercial address 62703. Thanks George.

I will check on shipping for you and see what I can do on the price.
Later,
Jon, 805-444-4489