Ignorant on tires and wheels

Chitoddy

Chitoddy

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Denver, CO
Ok, so I'm tire/rim ignorant and have been doing what I can to educate myself via posts on this site and general internet searches. I have to say thought that a lot of it is flying over my head (eg backspacing and other tire terms)- so I came here to post for maybe a short idiot guide or quick answer to my question - or at least direction to a post that could help me since there seem to be numerous.

I drive a 2001 SE. I bought it new in 2000 so it just turned 20. It has had the factory steel rims for all of those 20 years. As a 20 year present I want to finally get some new rims.

I believe those stock rims are 15X7.
My tires are currently Goodyear P235/75R 15/SL 105S OWL.
I have no lift.
I'm just a city boy who does city driving.
I see some rims I like that are 15X8.

I don't need a huge tire, but i'm fine with a little bigger but don't really want to be concerned about rubbing etc. I see lots of discussion about 31 tires being the biggest but might rub. I'm very confused about how that 31" compares to the tire that I have today since maybe its in metric above?

My basic question is can I buy the 15X8s take it to a tire place and just get a similar tire to what I have today and be good to go? Are there any negative effects of the 8 vs 7 on my SE? If I wanted to go a little bigger and not affect periodic highway driving what am I good with? Any other friendly info you can give this tire idiot.

thx - tc
 
You should be fine with an 8” rim. The following are the specs for the tires you currently have.

Specifications:

  • Size:
    • Wheel Diameter: 15
    • Aspect Ratio: 75
    • Section Width (Cross Section): 235
    • Overall Diameter: 28.9
    • Rim Width Range: 6.0-8.0
    • Weight: 28
  • Tread & Traction:
    • Tread Depth: 13
    • Tread Grade: 300
    • Traction Grade: A
  • Safety & Performance:
    • Load Index: 105
    • Max PSI: 36
    • Speed Rating (up to X mph): Up to 112 mph
    • Temperature Grade: B
    • Vendor Product Number MPN: 795698918
    • Global Trade Item Number GTIN: 697662011897
 
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Yes, you can buy the 15x8 wheels and put the same tires you have now on them.

A 15x8 is more common than a 15x7. The only real difference is that given the same size tire, the 15x7 would make the sidewall balloon out more, whereas the 15x8 would stretch the sidewall just slightly more.

For your 4-cylinder I would suggest not going over a 31" tire. For that setup, all you really need is a 1" spacer lift to maintain the factory level of up-travel.
 
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Chris said:
Yes, you can buy the 15x8 wheels and put the same tires you have now on them.

A 15x8 is more common than a 15x7. The only real difference is that given the same size tire, the 15x7 would make the sidewall balloon out more, whereas the 15x8 would stretch the sidewall just slightly more.

For your 4-cylinder I would suggest not going over a 31" tire. For that setup, all you really need is a 1" spacer lift to maintain the factory level of up-travel.
Click to expand...
Do you know the max size that fits the spare with keeping the brake light?
 
Chris said:
I do not as I’ve never run a third brake light.
Click to expand...
thx again. one more question (and I appreciate your quick responses very much), I'm getting rid of the faded milk jug bumper ends and replacing with simple caps. Is that Jug what a 31 would normally potentially rub against at full turn- if I did want to go to a 31? or is it something else in the jeep.
 
Chitoddy said:
Do you know the max size that fits the spare with keeping the brake light?
Click to expand...
I'm running a 33" with the stock third brake light. A 31" is absolutely fine.

A 15x8" wheel is common and great for a 31x10.5" tire. Just get a wheel with 3.75-4" backspacing.

That will probably be fine for stock setup, but due to the fact your rig is 20 years old, your springs are probably sagging 0.5". A 1" body lift is a simple way to regain what is lost, or a 1" spacer lift, which is cheaper, but more labor intensive.
 
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Chitoddy said:
thx again. one more question (and I appreciate your quick responses very much), I'm getting rid of the faded milk jug bumper ends and replacing with simple caps. Is that Jug what a 31 would normally potentially rub against at full turn- if I did want to go to a 31? or is it something else in the jeep.
Click to expand...

Those stock jugs are fine even with 33s in my experience. They are just likely to get damaged or rip off when on the trail, which is why most people get rid of them (that and they are ugly too).
 
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Chitoddy said:
thx again. one more question (and I appreciate your quick responses very much), I'm getting rid of the faded milk jug bumper ends and replacing with simple caps. Is that Jug what a 31 would normally potentially rub against at full turn- if I did want to go to a 31? or is it something else in the jeep.
Click to expand...
31's won't rub the jugs. They will rub the front control arms if you have wheels with stock backspacing (I believe it's 5.25"). That's why I suggested getting wheels with 3.75-4" of backspacing. What that does is move the wheel (and tire) away from the control arms, so that when you turn at full lock, they clear.
 
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Chris said:
I do not as I’ve never run a third brake light.
Click to expand...
thx again. one more question (and I appreciate your quick responses very much), I'm getting rid of the faded milk jug bumper ends and replacing with simple caps. Is that Jug what a 31 would normally potentially rub against at full turn- if I did want to go to a 31? or is it something else in the jeep.
JMT said:
31's won't rub the jugs. They will rub the front control arms if you have wheels with stock backspacing (I believe it's 5.25"). That's why I suggested getting wheels with 3.75-4" of backspacing. What that does is move the wheel (and tire) away from the control arms, so that when you turn at full lock, they clear.
Click to expand...
super helpful. All responses have been super helpful. I feel like I can go into the tire place and know what I'm talking about to a degree now. Or at least the right questions to ask. The 15x8 rims i want have 3.75 Backspacing - so should be good there. Looks like I'll just need to inquire about the 1" lift. Big thanks.
 
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Chitoddy said:
I feel like I can go into the tire place and know what I'm talking about to a degree now. Or at least the right questions to ask. The 15x8 rims i want have 3.75 Backspacing - so should be good there. Looks like I'll just need to inquire about the 1" lift. Big thanks.
Click to expand...
That backspacing is good. You will probably be fine without the 1" lift. If you want to know where you are, go out with a tape measure and measure your front springs, not including the stock rubber isolator at the very top. Stock spring length up front is 12". I suspect yours is running in the 11.5" range due to age and sag. Again, even that may be fine with 31's. I'd do that, then just go ahead and get the tires and see how they are at full lock, and solve the problem after if there is one. You can always decrease your turn radius by putting some washers on the steering lock. That will stop the tires from rubbing the control arms if they did. Basically, a free fix.
 
JMT said:
That backspacing is good. You will probably be fine without the 1" lift. If you want to know where you are, go out with a tape measure and measure your front springs, not including the stock rubber isolator at the very top. Stock spring length up front is 12". I suspect yours is running in the 11.5" range due to age and sag. Again, even that may be fine with 31's. I'd do that, then just go ahead and get the tires and see how they are at full lock, and solve the problem after if there is one. You can always decrease your turn radius by putting some washers on the steering lock. That will stop the tires from rubbing the control arms if they did. Basically, a free fix.
Click to expand...
Will measure and see. What is the negative if spring coil isn't long enough? A loss in my clearance when going over things? Anything else?

She's in the shop getting alternator replaced today. thx again!
 
I also know nothing about tyres and rims. Wanted to be a penny pincher and put narrower width winter tyres, so found these rims on local internets. Will these fit our jeep? Owner says central bore is 71.6mm. if yes, what size is the narrowest width tyres i can put on them?

Screenshot_2020-11-17-23-56-39-722_kz.slando.jpg


Screenshot_2020-11-17-23-56-35-507_kz.slando.jpg
 
3.75 is the absolute perfect BS for our Jeeps.
Having said that you should know these will make your tires stick out past your flare. Not much...but it definitely will about an inch or a little more.
I don't know the laws in Illinois with flares and tires sticking out past them...etc.

In PA we aren't allowed any stickout beyond the flare. How hard is this enforced? Not much provided you aren't ignorant to the law with your tires like 8 inches out past.

I'm sure even if your laws are like my communist state you'll still be ok with 3.75 BS.
I think you'll love how it looks and should you ever need to sell them they'll go really quick.

Good luck

P.s.

You can fit a 31 all day long on there. Don't fret over that. I promise it will fit on there just fine.
 
Chitoddy said:
Will measure and see. What is the negative if spring coil isn't long enough? A loss in my clearance when going over things? Anything else?

She's in the shop getting alternator replaced today. thx again!
Click to expand...
The negative is you have less clearance over the tire, and more likely to rub or bottom out your shock, especially if you went off-road.

In the end, think about it, your rig is 20 years old. There's no doubt the suspension should be upgraded anyway.

I just got a 1991 Jeep Cherokee XJ. It is a bit of a pain due to rust, but I am in the process of replacing the suspension. It will be soo much better, drive like or better than new when I get done.

Do you have to replace all this stuff? No.
 
JMT said:
The negative is you have less clearance over the tire, and more likely to rub or bottom out your shock, especially if you went off-road.

In the end, think about it, your rig is 20 years old. There's no doubt the suspension should be upgraded anyway.

I just got a 1991 Jeep Cherokee XJ. It is a bit of a pain due to rust, but I am in the process of replacing the suspension. It will be soo much better, drive like or better than new when I get done.

Do you have to replace all this stuff? No.
Click to expand...
These are absolutely things I want to consider doing now however - I haven't done shit to her in years and want her to last another 20 if possible. Is regearing a concern for a move from 29" to 31" if i chose 31? Or is that not enough to really matter. I've been 20 year used to the fact that on an uphill on an interstate that "she's givin' her all she's got Captain!".
 
Chitoddy said:
These are absolutely things I want to consider doing now however - I haven't done shit to her in years and want her to last another 20 if possible. Is regearing a concern for a move from 29" to 31" if i chose 31? Or is that not enough to really matter. I've been 20 year used to the fact that on an uphill on an interstate that "she's givin' her all she's got Captain!".
Click to expand...
Need more info.

6 cylinder or 4?
What gear ratio?
What transmission?

Most people don't re-gear moving from a 29-31" tire.
 
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Turdworlder said:
I also know nothing about tyres and rims. Wanted to be a penny pincher and put narrower width winter tyres, so found these rims on local internets. Will these fit our jeep? Owner says central bore is 71.6mm. if yes, what size is the narrowest width tyres i can put on them?

View attachment 204034

View attachment 204035
Click to expand...
I don't know. I have to know the bolt pattern. TJ's are a 5x4.5 or 5x114.3 in metric
 
JMT said:
Need more info.

6 cylinder or 4?
What gear ratio?
What transmission?

Most people don't re-gear moving from a 29-31" tire.
Click to expand...
It's an SE 2.5L - so 4 cylinder.
Manual transmission.
No clue what the gear ratio is - whatever came out the factory.
 
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