Looking to do an Endurance race at a track I have never driven a 4 cylinder on and trying to figure out the best tire to run. On this focus everything has to be completely stock so the only change to make is tires to try to get in to the sweet rpm spot on this 3/8 mile asphalt oval.
My choices I am looking at right now are the extreme ends for tires to try to be about 70mph at the end of the straightaway.
What would be a better choice? I can get 215/65r15 tires and run the manual in 2nd gear and just barely hit rev limit at 70mph...or I can get 185/55r14 tires and shift to 3rd gear and be in a good upper rpm and run up to 75-80mph if needed? From few guys I talked to they say they would hit 70mph with their cars (none with the same make car) but they are only guessing nobody has had a speedo so still asking around. I keep thinking we could hit 75mph but I am at this point only estimating also.
considerations of 215/65r15 ... they are 1.5 inches wider tread than the 185/55r14 and these tall tires in 2nd gear should pull off the corner very well but could possibly be out of rpm before the end of the straights
considerations of 185/55r14 ... the car would have a lower center of gravity and sit 2 inches lower but sacrifice the wider tires ... in 3rd gear I would have the ability to go past 70mph and still be in upper rpm range just in case the track is as fast as I think
It would stink to have the taller tires and find out most everyone can go faster and I would have to shift to 3rd and be way out of my good pulling rpm range. Then again it would stink to find out we can only hit 65mph and the tall tires would have been perfect around rev limit and if I had the smaller tires 3rd gear at slower speed would be out of rpm range for pulling off the corner well.
Any advice is appreciated .... so a 2 inch lower car going around the corner vs a taller wider tire that should have one and a half inch more tread on the ground per tire?
Tires must be stock passenger minimum 400 treadwear
Thanks, I will check in again tomorrow night and hopefully have some experienced racers and setup people chime in with their thoughts.
You may want to consider looking for a durable tire rather than the perfect size. Asphalt ovals destroy street tires quickly and you will be limited to a few Brands and sizes that will hold up. If this is a circle track with a stock class, find out what the stock class cars are running for tires and use them regardless of whether they are perfect size-wise or not. Since it's an endurance race, seconds per lap probably will be less important than reliability and quick pit stops. Having said that, I expect you'll find most cars are running 15s and you will have trouble finding a durable sticky 14-in Street Tire.
In reply to machfive :
Well for an oval you'll want 4 different tires. On the car. The rear right tire is your tallest and widest. It also has the highest tire pressure.
Your left rear is short. Talk to the locals just how much stagger you want. It really depends on the track itself. If it's more of a circle than anything and you have an open differential you'll run about 80% of the right rear.
Now if it's more of two straights followed by circles at each end. ( looks like a paperclip) the difference will be more like 60% in stager, inside to outside.
Finally if it's 2 straights with 2 sharp corners followed by 2 more sharp corners ( more of a rounded off rectangle.) that's going to be more like 35-40% inside to outside.
The front left is your absolute shortest tire with the lowest tire pressure. In size the right rear is the tallest/widest. The right front is next talk /width. The left rear is 3rd tallest width. And the left front is the shortest narrowest.
Use your temperature guage to adjust tire pressures. Right rear should be the hottest. Followed by left rear. Followed by right front and finally left front.
You might want to preload the sway bars. How much depends on the track.
Properly set up you can put a brick on the throttle and it will go around the track by itself. (. I e never actually seen that happen but we all pretend that's the goal.
Alignment? aw, just try to keep the tires a little hot on the inside edge
In reply to bearmtnmartin (Forum Supporter) :
This is only the 3rd time this race has been run and from what I have heard most have just run the softest tires allowed which is 400 and they have held up well ... have not heard of many tire troubles from anyone but I am still asking around.
Since cars are completely stock I am mostly concerned with being in a good rpm at the end of the straights. This is a 6 hour race with running 2 hours at a time and then refueling and switching drivers. Decent banking on egg oval so does not destroy tires.
For smaller tires of 185/55r14 I am looking at Haida HD921 which are 400AA and have good ratings. The tall tires of 215/65r15 possibly BlackHawk Street-H HH11 which are 420AA. Both should hold up well so getting up to speed is of concern. I know I will need some stagger and plan to have some and still calculating that also. I dont expect to find the perfect size but want to be in the ballpark and not be lugging out of the corner so seconds per lap will be of concern for me.
Thanks for the input ... anything else helps
In reply to frenchyd :
I appreciate the lesson in stagger (very helpful) and will use the most I can in rear and some in front. We must use same wheel size all corners ... this front wheel drive I would like the fronts to be close to rev limit on straights and not bogging the engine down coming out of the corners. I do have LSD so hopefully both tires will pull me around the corner. I do have a good racing line and am mostly concerned with the faster cars toward the last 2 hours of this 6 hour enduro. --- the car should last as long I can avoid accidents which I normally do well at --- the track is egg shape oval with decent banking ... I am still trying to talk to locals but not a lot of info yet. I was hoping to find out if it was worth putting on smaller tires and sacrificing tire width for a 2 inch lower center of gravity which theoretically the car would not roll over and put so much pressure on outside tires...and rpm is a big concern
....anything else is helpful...thanks
Preloading sway bar is good tip also
in a 6 hour oval enduro of fwd bangers, surviving the whole race is going to be your biggest hurdle, more so than finding the perfect rpm on the straight, IMO. A couple of spare wheels/tires is probably a good idea. Trying to dial in the *chef's kiss* "perfect tire stagger" would be somewhere near the bottom of my list.
Dial in as much negative camber as you can get in the RF and as much positive camber as you can get in the LF. Trying to find the perfect tire diameter without a bit of very specific gearing calculations is going to be tough - more of a trial and error scenario. What car are you running? where's the race? Do you have any opportunity for on-track testing before the race? Good luck!
In reply to machfive :
How long is this actual race?
I second the need for stagger, and I wouldn't discount the need to be in the right rpm range for the duration of the event. I'd go with the combination that allows you to not shift at all during the event. You got enough going on in an enduro to worry about shifting.
I've done a fair bit of fwd circle track racing. At least here in SW Florida, the rules state that all of the tires must be the same size. Rules may be different in other areas. Endurance racing on an oval is a bit different than a road course. Lots more carnage on the oval. Avoiding the crashes is the name of the game.
In reply to Lof8 - Andy :
I know surviving is the key but just in case I want to be fast of course. This car has the potential to be up front and I have experience at this track just not in this car. Spares I will have on hand and have considered getting both sets of tires and change after the mandatory pit refuel break every two hours if the one set is not working out but did not want to spend so much on tires if not needed.....but guess they will be used at some point anyways.
Suspension has to be stock so no camber except what I can pull on spindle when tighting it up to the strut so not much at all...but I will pull hard ..lol I realize finding perfect diameter right off will be hard but wanted a good ballpark .....and to see what others thought of as more important in this type of tire selection to see where the car will sit with ride height or having more rubber on the ground as a preference? Have a Low center of gravity so tires should not roll over the sidewall so much and grip better or wider tires with much more tread on the ground but may roll over since the car is two inches higher? But would the wider tires compensate for the increased ride height? Running a Toyota Celica in Amherst, Ohio and I don't think anyone will have the opportunity for testing before.....that would be great but don't expect it. Thanks for the luck I will need it in traffic with about 40 cars. I have survived the two other enduros before but only been a top 5 car with other low horsepower cars...hoping this car and a good tire setup... dealing with a completely stock car should put me in victory lane. I have won many races but the enduro is a new animal. Thanks again.
Looks like it's 3/8 mile with pretty good banking. I'd think the bigger/wider tires would be the better choice, but I'm just guesstimating with a lot of variables. If they allow stagger, maybe the smaller size on the left side would be an advantage. Sounds like it'll be a fun race!!
In reply to J.A. Ackley :
The race is 6 hours long but you have to stop every two hours and will have a chance to refuel, work on car, change drivers...etc ...for about a 10 minute break...then get right back at it.... I will drive the first leg, have my son who is a good racer with experience run the second leg and I will run the third two hour stint. An inch or more of stagger in the rear is the plan and a slight amount in the front (still trying to find out what others have been successful with)
I am concerned with being in the right rpm range hence this post...either of the choices I have in previous post of smaller tire in 3rd gear or larger tire in 2nd gear would make it so I don't need to shift..not planning on it. I am afraid of still running in 2nd gear with tall tire and having to lift early before corner entry and coasting because I hit the rev limit just past the start/finish line. It would be a rocket off the corner if it works out that 70mph is the target speed before lifting but you are right shifting would lose too much momentum and too much to worry about watching traffic.
In reply to Lof8 - Andy :
Thanks for the input. I am considering the bigger tires also because the first few hours of the race will be mostly traffic and I will not be able to run flat out until later when attrition takes out half the field...then the last 2 hours will be fast and should be a blast. They do allow stagger (tires are the only change allowed from a factory car) and I plan on it and I am still asking around for the amount most run at this track.
To go fast on an oval you also want all the weight on the left side of the car. Anything you can offset to the left should be on the left, you should make the car much lighter than the rules allow and then place weight under the drivers seat to meet minimum. Rednecks done figgered all this out a long time ago, enjoy!
Stagger and weight are your new friends.
So one vote for keeping taller wider tires.
Anyone else want to give their thoughts?
Main question is would you lower the car two inches with smaller tires and sacrifice the wide tires and lose an inch and a half worth of tread at each corner? Would the lower center of gravity be worth losing rubber on the ground and possibly help since the tires should not flex as much on the sidewall and still stick in the corner because the weight being transferred is lower?
If possible I'd test both to confirm, but my hunch is the wider tire will be better in this case.
Peabody
MegaDork
2/23/23 10:01 a.m.
machfive said:
Anyone else want to give their thoughts?
In my experience you will be faster on the smaller tires, but that's not a lot of rubber for a car that size, and you may very well destroy them in a race that long. Neither size is ideal. Run lot's of tire pressure, like in the 40 range.
I don't think there's anything to be gained running stagger on an open diff FWD car. But if you do, whatever you run on one corner, offset the diagonal corner to match, otherwise you will upset the handling, and not in a good way.
If you make it to the last few hours prepare to be fast. These races often pay money, our local enduros are 10 grand to win, so they attract some good drivers.
Stagger is also a cheap way of preloading the suspension.
The tire size and overall ratio you choose will be down to where you hit the rev limiter on the track. Ideally on a 3/8 you will want to hit it going into the corner. I've seen some manual cars 4 cylinder cars running a 3/8 dirt hitting the rev limiter at the flag stand which resulted in them getting pulled down the straight but automatic cars. Each transmission will be different aswell with various different ratios. On the j body the answer for manual guys is to swap in a manual from a Saturn vue which has like a 4.30 or 4.41 final drive and run in 3rd gear. The automatic j body has a 3.63 so they just run in second. Another manual j body which I dint know which transmission it runs shifts up a gear halfway down the straight.
In reply to Peabody :
I realize that both my tall choice and short choice are not the greatest but should get me close (at least on paper and from talking to others about the speed) to the rev limit at the end of the straight so it should be fast. I am trying my best preparing to be fast and last until the end....I believe this will pay $3500 to win so some good cars are going to show up..but mine should be very competitive and my experience at this track and others in a different car will help a lot. Thanks
One consideration is that shifting gears frequently adds a failure point to what is likely already a hot transmission from the amount of work the differential will be doing.
In reply to red_stapler :
You are right...the goal is not to shift and be in good rpm range.....so far need more input on what would be the best tire choice (size) to start out? Short ones that have the car lowered 2 inches or tall fatter tires that are an inch and a half wider?
In reply to red_stapler :
You don't shift in oval track applications
Peabody said:
In reply to red_stapler :
You don't shift in oval track applications
Some in 4 cylinder racing have to depending on the ratios they have and track size
In reply to machfive :
It really depends on the speed. 1/4 mile track typically will run in 2nd gear and 3/8 mile will run in 3rd gear. ( of a 4 speed. ( 5 speeds 5Th is over drive) Final selection is based on tire. Taller lowers revs shorter raises revs.
Find the power curve of your engine. It's someplace on the net.
Redline is likely not peak power.
You'll want to be at peak power about 3/4 of the way down the straight. That's where passing occurs.
Over fill the engine by enough so it slightly smokes the reason is under braking and cornering oil will climb up the oil pan away from the pickup. Thus starving the engine from the oil it needs to stay together.
I am leaning toward the taller wider tires as some have suggested.
Anyone else think the smaller tires that will make the car 2 inches lower will help with cornering? Or them being an inch narrower will not be enough rubber to keep corner speeds up?
