How bad will a 245/50/16 vs. 225/50/16 hurt my E/T's

[Gooberlog]

Not sure if this should be in the Handling tech forum or if the Drag section applies?
I've been around long enough to know to search before posting. With that being said, I found similar posts but not quite the info I'm looking for.
I have a set of FD wheels w/ 10mm spacers going on my '92 awd but I need to get tires for them first. The car is not my daily driver and will be used for 1/4mile track and street cruising. I am not concerned about handling of the car as it is primarily a straight line vehicle. The car will be running a modded 14B for a while with a strict weight diet (hence the light FD wheels). I've researched and found that i can run a 225 to 245 width tire on the FD wheels. I was planning on running a 225/50/16 tire but a friend has a set of like new BFG street tires in a 245/50/16 size for a good price. Some some questions i have for the tire gurus are:

1) Will there a be a big weight difference between a 225/50/16 and a 245/50/16? (every pound counts- especially rotating mass)

2)How much taller is a 245/50/16 than a 225/50/16 in inches?

3)With the 245 being a taller tire, how much will my gearing be effected from the stock 205/55/16 tire size and what kind of trap speed and 60' time differences should i expect on a mid 12 second car trapping 110-14?

4) less importantly, how far off will my speedo be with either tire?

5)and should i expect any rubbing with such a wide tire even with the 10mm spacers?

Thanks guys, i know these questions seem kinda NOOB like but i have had my hand dipped inside all kinds of dsm related mods but never ran different wheels and tires on one.

Gooberlog

 

[silvreclips]

The first number refers to the width of the tire. So the 245s are going to be the same hieght at the 225s. If stock tires are 205/55 and your going to a 2xx/50 you are actually going to a smaller tire as far as hieght goes so your speedo is going to say your going faster than you really are. Shouldn't be off by much. Maybe 5mph at 60.

I cant answer all of your questions but this should give you some help

 

[Gooberlog]

The first number refers to the width of the tire. So the 245s are going to be the same hieght at the 225s. If stock tires are 205/55 and your going to a 2xx/50 you are actually going to a smaller tire as far as hieght goes so your speedo is going to say your going faster than you really are. Shouldn't be off by much. Maybe 5mph at 60.

I cant answer all of your questions but this should give you some help

Thanks for the reply.
I'm aware that the first number in a tire size is the width, the second the height/profile and the third the wheel diameter followed by speed rating and so on.
The second number in a tire size (profile) is a fraction of the overall width of the tire. So if you have the same number for a sidewall profile (50) but a wider tire (245 vs 225) the sidewall or profile of the tire will be taller. I just did a tire comparison on tirerack.com, if you select two or more tires of the same size and click compare selected tires, it will give you in depth info on the tire including tire diameter. I then did the same for the larger 245 tire and found that both 225/50/16 tires had a diameter of 24.9" and the 245/50/16 was 25.7". So in this example the 245/50/16 tire would be .8" taller than the 225/50/16.
This wouldn't make much difference on a big truck but on a dsm an inch taller tire would probably look like a balloon.

Disregard question #2 as i have just answered myself thanks to tirerack.com

 

[Gooberlog]

I think if anyone can answer these questions it may help someone in the future with the same dellema, but I have decided to go with the 225/50/16 after talking to a tirerack.com representative. I called up asking for the tire weight of my preferred tire of each size and the wider BGF's were an extra 4pounds per corner based on a larger tire and a different compound. Another 16 pounds of rotating mass kinda defeats the idea of running the light FD wheels in the first place as I'm running them more for the weight savings than the extra traction from a wider wheel.

 

[ryguy86eklipse]

Sounds like we have the same setup. I will be running 225's as well. I've heard great things on the dunlop direzza z1 star spec's and they're 130 or something I believe on tire rack. I'm going to the tuning shop to get an opinion on what size spacer I need to run. Although you answered your own question, from the research I've done it seems 245's require the 15mm spacers in the rear and front. The shop said that coilover's may also help reduce the need for a larger spacer, but will try to update you tomorrow after I take it in. Sorry for the long paragraph but i'm on my cell phone! Hope this helps. - Ryan

 

[Gooberlog]

Sounds like we have the same setup. I will be running 225's as well. I've heard great things on the dunlop direzza z1 star spec's and they're 130 or something I believe on tire rack. I'm going to the tuning shop to get an opinion on what size spacer I need to run. Although you answered your own question, from the research I've done it seems 245's require the 15mm spacers in the rear and front. The shop said that coilover's may also help reduce the need for a larger spacer, but will try to update you tomorrow after I take it in. Sorry for the long paragraph but i'm on my cell phone! Hope this helps. - Ryan

That's cool, let me know what you find out. I will eventually do a lowering spring set up 1-2" eibach kit but not coil overs. I'm planing on buying a set of sumitomo HTRZ from tirerack.com they got really good dry weather traction reviews and are only $65 ea!

 

[matthewdesigns]

Please follow up with your impressions of these tires. I had never heard of them, but after reading all the reviews on Tirerack.com they definitely look like a good buy. I'll be needing to replace my summer tires this year, so these are on the watch list now for sure.

 

[silvreclips]

I got some HRIIIs last summer. 225/45/17 I like them so far, they have 10 passes at the track and 10 laps during an autox. I need to rotate them now but the front still have over half the tread and the back has 85% or so. They handle pretty well for a cheaper tire.

 

[Gooberlog]

Please follow up with your impressions of these tires. I had never heard of them, but after reading all the reviews on Tirerack.com they definitely look like a good buy. I'll be needing to replace my summer tires this year, so these are on the watch list now for sure.

I'll let you know, but it will be a little while as i'm buying them to pass State inspection to get the vehicle tagged and on the road. But after i log some miles on the street with them i'll let you know.

 

[ryguy86eklipse]

I took it to the shop yesterday and they said that with a 5mm spacer it would be really tight, and may need the control arm grinded slightly even with the coilovers installed. I may go with a 10mm spacer, I believe it's through Eibach as I'd rather not grind the control arm and the shop said they wouldn't do it personally. I'm in a debate with whether or not it's worth the cost of spacers, but more importantly the peace of mind of just going with some evo 8 enkei's. They have some laying around at the shop... :-/

Anyways, I most likely will stick with the RX rims for now and just go the route of spacers. If there's anyone who's auto-x'ing or road racing on this wheel/spacer setup, please chime in! The reassurance that others have ran it successfully would be nice

 

[Gooberlog]

Yeah I decided to run the RX7 wheels for the weight savings and they look a hell a lot better than the stock laser wire wheels. I'll be using the car for street driving and the drag strip. If you already have the RX7 wheels I would give them a shot, but if you don't have them yet you may just want to pick up the EVO8 wheels.
If you do end up running the FD wheels, you might want to consider longer wheel studs. I've been told with the different offset and the use of the wheel spacers that you don't have a lot of thread to turn the lug nuts on to, and i think you may have to run different lug nuts because the dsm ones may be too fat for the RX7 wheels. Just a couple more things to consider. Kinda sounds like a pain, but i got a good deal on mine so i'm on a mission.

 

[Slippi84]

But you need to think about how much power you plan on making as well as the more power you make the more you will need help with traction. A 245 tire would have given you a larger footprint or tire patch that is actually in contact with the ground at any given point. I plan on running running 245 maybe even 255 wide tires if they don't rub in an attempt to get as much traction as possible. Four pounds a corner is a good sacrafice for traction. Especially with a turbo like a 14b that starts kicking almost right out the gate.

 

[Gooberlog]

My last 1g ran a best of 12.003 on a big 16g and traction was never an issue at my local track with the stock size 205/55/16. I'm thinking with a much lighter wheel they are more susceptible to break loose but then i feel that the extra 20mm of rubber at each corner should even that out. I'll be pushing the 14b on this laser for a while and have final plans of a basic set up with a 50trim or similar turbo and maybe some alcohol injection. I'm thinking that traction with the 14b set up should not be too much of an issue with the 225/50/16s on the fd wheels but it may become an issue at high boost with a larger turbo, but that will be a while from now I have plenty of time to consider wider tire options for traction purposes.
Thanks for the feedback and you made a very valid point. BTW: I love your car!

 

[viperlp01]

I always thought that the 1st number was a fraction of the the rim size... My mom has a 1500 ram with 20s and she has 255 50 20 and the rubber is pretty thick so i figured the whole wheel is now 30in big(from bottom of rubber to top). I could be wrong but honestly i could not imagine that wheel getting much taller from your point of view...

 

[matthewdesigns]

Tire sizes are read like this. Using a 245/45/17 for example:

245 millimeters wide
45% of the 245mm width is the sidewall height
17 inch rim

So, to figure the entire diameter of that tire:

45% of 245 is ~110mm. Multiply by 2 = 220mm. This is the total amount of sidewall in the diameter of the wheel/tire combo.

Divide 220mm by 25.4mm/inch = aprox 8.6". This converts millimeters to inches.

So the total diameter of a 245/45/17 tire is 17"+8.6"= 25.6"

The reason it works using half the rim diameter of your mom's wheel/tire combo is because her tires are aprox 10" wide, so it's merely coincidence that get you to the same answer as using the correct way laid out above (30").

 

[Gooberlog]

Tire sizes are read like this. Using a 245/45/17 for example:

245 millimeters wide
45% of the 245mm width is the sidewall height
17 inch rim

So, to figure the entire diameter of that tire:

45% of 245 is ~110mm. Multiply by 2 = 220mm. This is the total amount of sidewall in the diameter of the wheel/tire combo.

Divide 220mm by 25.4mm/inch = aprox 8.6". This converts millimeters to inches.

So the total diameter of a 245/45/17 tire is 17"+8.6"= 25.6"

The reason it works using half the rim diameter of your mom's wheel/tire combo is because her tires are aprox 10" wide, so it's merely coincidence that get you to the same answer as using the correct way laid out above (30").

Well said.

 

[PIMking]

Please follow up with your impressions of these tires. I had never heard of them, but after reading all the reviews on Tirerack.com they definitely look like a good buy. I'll be needing to replace my summer tires this year, so these are on the watch list now for sure.

The company I drive dump truck for has a tire shop and they sell a TON of sumitumo tires for semi's and dump trucks. I actually have them on my truck now and if they are good for that I assume the street tires are just as good.

 

[Gooberlog]

I had my mind set on the sumitomos but today my buddy said that a friend of ours has a pair of brand new BFG g-force tires in a 225*50*16 for free, so i think i'll just be buying another pair of these, but if that doesn't work then i'll roll with some SUMI's

 

[Black_Bullet]

But you need to think about how much power you plan on making as well as the more power you make the more you will need help with traction. A 245 tire would have given you a larger footprint or tire patch that is actually in contact with the ground at any given point. I plan on running running 245 maybe even 255 wide tires if they don't rub in an attempt to get as much traction as possible. .

It could help traction but also cause more rolling "friction" the rest of the way down the track were the additional traction isnt needed anymore. This is why in the Evo world a lot of guys are running motorcycle slicks now days with real good results.

Yeah I decided to run the RX7 wheels for the weight savings and they look a hell a lot better than the stock laser wire wheels.

A 92 Laser AWD with FD3S wheels... Hmm that sounds familiar.

The rx7 rims have 50mm offset I believe which makes it hard to get any meaty tires in there on a DSM. Coilovers and thicker spacer or longer wheel studs will give more clearance if you ever decide to go with the wider tires. Or just keep the 225s on there and do 10mm spacers ( preferably hub centric) and then you wont need coilovers for clearance. But you will need to grind a bit of the metal off of the control arm in the rear or else it will rub your tires.
When you go to mount the tires you will see what I mean.GL

 

[Gooberlog]

sounds good will do!

 

[Slippi84]

It could help traction but also cause more rolling "friction" the rest of the way down the track were the additional traction isnt needed anymore. This is why in the Evo world a lot of guys are running motorcycle slicks now days with real good results.



A 92 Laser AWD with FD3S wheels... Hmm that sounds familiar.

The rx7 rims have 50mm offset I believe which makes it hard to get any meaty tires in there on a DSM. Coilovers and thicker spacer or longer wheel studs will give more clearance if you ever decide to go with the wider tires. Or just keep the 225s on there and do 10mm spacers ( preferably hub centric) and then you wont need coilovers for clearance. But you will need to grind a bit of the metal off of the control arm in the rear or else it will rub your tires.
When you go to mount the tires you will see what I mean.GL

If you have a car making real power keeping traction isn't just a off the line thing it's a whole track thing. As a matter of fact most real race cars lose traction further down the track not at the line because they roll out the hole.

 

[Black_Bullet]

If you have a car making real power keeping traction isn't just a off the line thing it's a whole track thing. As a matter of fact most real race cars lose traction further down the track not at the line because they roll out the hole.

Being that he's awd, and being that he said he's only going to be running a 14b, I dont think he will have traction problems down the track.

 

[Gooberlog]

Being that he's awd, and being that he said he's only going to be running a 14b, I dont think he will have traction problems down the track.

Yeah these are all valid points and my long term goals of the car is only 11 second street car and still i want it to be well mannered so traction shouldn't be my biggest issue.

 

[UofACATS]

This is a quick and easy calculator.

Tire size calculator

2)How much taller is a 245/50/16 than a 225/50/16 in inches?

3)With the 245 being a taller tire, how much will my gearing be effected from the stock 205/55/16 tire size and what kind of trap speed and 60' time differences should i expect on a mid 12 second car trapping 110-14?

4) less importantly, how far off will my speedo be with either tire?

 

[GDNF2ET]

I was thinking about going with a 205/60/16 on my 16x8 SSRs..The tires are generally lighter and will still give me the extra height I need right now..Any thoughts on the General Altimax HP tire ?