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John McCormack

Tyres on a 4.5" rim

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My daily driver TR2 tyres need replacing. I currently have 165/80/15 tyres on chrome 60 spoke 4.5" rims.. 

I am looking at 175/80/15 replacements.

Has anybody any advice on these larger tyres on 4.5" rims?

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FWIW I have 165/80 15 on my 5.5" TR6 rims and the look fine, so I would not recommend going any bigger on your 4.5" rims

Bob

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It’s not best practice to use tubes in low profile tyres even though 70 series isn’t low by today’s standards.; I’ve assumed that your wires aren’t the tubeless type. 
I stick with 165s even on my 5.5 rims to keep the handling predictable, the steering light(ish) and the stub axles intact. 
 

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Thank you all. They are tubeless rims and work well having been on the car for 5-6 years, about 30,000 miles. I want the extra rolling diameter of the slightly bigger tyre and a decent 175 tyre is now available here.

Looking at comparison sites like this link below a 4.5" rim can handle up to 185 tyres.

 https://www.tyresizecalculator.com/tyre-wheel-calculators/wheel-rim-size-calculator

I have confirmed that 175/80 is ok on a 4.5" rim. I will give them a try.

 

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10 hours ago, John McCormack said:

Thank you all. They are tubeless rims and work well having been on the car for 5-6 years, about 30,000 miles. I want the extra rolling diameter of the slightly bigger tyre and a decent 175 tyre is now available here.

Looking at comparison sites like this link below a 4.5" rim can handle up to 185 tyres.

 https://www.tyresizecalculator.com/tyre-wheel-calculators/wheel-rim-size-calculator

I have confirmed that 175/80 is ok on a 4.5" rim. I will give them a try.

 

 

I would be interested in how it works out.  Please and thank you.

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The tyre place had disposed of their wire wheel adapter for the balancer some years ago.

However, we took the two front wheels off and with the old tyres still on put them on the balancer with the normal cone on the inside of the outboard of the wheel centre. The wheels ran perfectly true so we put new tyres on the wheels and had no trouble balancing them. I only got to 70km/h on the way home so haven't really tested them but they felt really good with what I could do.

I can only assume that these 60 spoke chrome wheels, bought through the TR Register Australia (Moss Europe supplied) in 2014, are machined on the inside of the wheel centre so they can be balanced without adapters.

My old wheels, probably dating from the 50s, could not be balanced in this way.

The 175 tyres do make a small but noticeable difference in speed. With the 165 tyres my speedo would read 39mph at 60 km/h. With these tyres it reads around 38mph. Pretty close to being correct at that speed.

There is no problem with the size. They are not oversized on the rim and being a bit taller they look better than the 165s.

Edited by John McCormack

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Got out onto a freeway today with the GPS and time to get accurate readings at higher speeds.

The bigger tyres give a 4% increase in road speed.

Previously 100 km/h was at 2500 rpm. Now at 2400 rpm. Or at 2500 rpm I was doing 100, now I'm doing 104 km/h. Normal cruise at 110-115 is close to 150 rpm lower.

It is a significant improvement and the speedo is now quite accurate even at higher speeds.

There is an occasional vibration (through the car rather than through the steering wheel) between 93-97 km/h, it seems to depend on the road surface whether it occurs or not.

I got up to 124 km/h, oops sorry it was actually 110 (the speed limit). Apart from the vibration noted it was good at all speeds.

The steering is actually considerably lighter than before but the old tyres were very worn and 12 years old.

I'll chase up a better balance but I'm very pleased going to the 175 tyres.

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